Well, but keep in mind that the Vulcans are in fact a violently emotional people; they have just collectively chosen to repress those emotions because they led to so much self-destruction.
Obnoxious as they are, the Klingons have the virtue of being an open book and comfortable with themselves. Vulcans were presented as virtuously logical in the original series, but in TNG, one starts to see them portrayed as somewhat stunted and sneaky.
Actually, I was shooting for the “my favorite Jew” fallacy. It is said that when the Jews started getting rounded up in Germany by the Nazis, every German had a “favorite Jew”, that one friend or neighbor, who they would try to protect. They were fine with everyone else being rounded up, never making the leap to thinking that maybe all Jews were OK. The guy they knew just happened to be different.
I have met people who talk about, say, Muslims the same way. “Muslims are all terrible. Well, except for the ones at my workplace. They’re OK. And the guy who lives next door. Actually, every Muslim I know personally. But the rest of them are terrible!”
Klingons tell their children, “Run and bring me the scissors! Quickly!”
Regarding handrails: “Children and cowards use handrail.”
“Men do not roar. Women roar. And, they hurl heavy objects…and claw at you.”
“What does the man do?”
“He reads love poetry. He ducks a lot.”
It occurred to me that they became so popular during TNG because of how BLAND and boring the Feds seem.
If a douche like the Outrageous Okuna can come on board and be a rock star with the ladies, damn that is a bland society.
Klingons have some redeeming features even in TOS. Kor, from Errand of Mercy, resents the duty of “governing a population of sheep” and admires Kirk for being man enough to resist being pushed around. Kang, in Day of the Dove, is principled enough to prefer making peace with humans to being the plaything of the alien hate-creature. And if they’re sneaky rather than directly aggressive for most of the series, they are after all stuck with the reality - that the Organians won’t let them be as violent as they would like.
It’s been shown plenty of times in TNG and DS9 that Worf, as an outsider, had a pretty naive view of Klingon honor and society. My personal fanwank is that Klingon obsession with honor in the TNG era is a direct result of what happened in Star Trek 6. Before the Klingon concept of honor was in the service of realpolitiks. After pretty much losing the Federation-Klingon cold war they over compensated to save face and keep the empire intact.
In DS9 there was a lot of talk about the empire not being what it used to be. I think it was either Gowron or Martok that admitted that in a total war against the Federation the Klingons would be defeated. It is my belief that after the victory over the Dominion the empire would regain some confidence and a more practical outlook with regards to honor would reemerge.
Klingons have the best ship designs and weapon interfaces. When a battlecruiser or bird of prey is in your view screen, you feel it in your soul.
Their torpedoes growl out of the tube and flash with red rays of impending death as they travel, not like the friendly christmas lights that Federation ships use.
They don’t display a simple “target locked” message cooed by an AT&T operator. Their display lets the target ship know that it has been locked with malice, surrounding it with dominating multiple rotating orange triangles and Wagnerian klaxons.
No padded chairs and rounded corners on the helmsman stations. You are on station to fight, not to sense duality while your yeoman brings you tea.
Riker, of course, would have gotten his initial impressions from Worf, who never laughs. It’s like, since he was raised by humans, he thinks he’s always got to prove he’s more Klingon than the Klingons.
Fans dig Klingons because the Proud Warrior Race Guy is always cool, just so long as you don’t have to go anywhere near him in real life.
Klingons are like the “noble savages” that intrigue people of more erudite upbringing when they get bored with their own culture. Klingons don’t have to act polite or watch what they say. If there’s a conflict, they’re ready to fight and settle the matter right away, instead of resorting to equivocating. Their lives are more inherently dangerous and adventurous.
How often have you wanted to howl like an animal and scare away the annoying? Have your enemies scatter before you and hear the lamentations of their women? Carry around weapons legally? That’s the allure of Klingons.
Yeah, but people to whom that appeals forget that such a lifestyle often precludes living past 30.
Live fast die young leave a smelly hulking corpse?
Right. It’s fun to howl like an animal and scatter your enemies before you. It’s fun to say exactly what you want and not care what anyone else thinks. It’s fun to stab annoying people in the face.
Except if you actually were a Klingon, that’s exactly what you could never do. You couldn’t stab your annoying boss in the face, because your annoying boss would be a Klingon warrior who’d stab you in the face first. You couldn’t say whatever you wanted, because if you ever said anything annoying to another Klingon warrior, they’d stab you in the face. You couldn’t scatter your enemies before you, because they’d be just as likely to kick your ass as you are to kick their ass. You can’t stuff Todd into his locker when Todd is also a Klingon warrior, he’d stab you in the face. You think the bullying is bad from Todd the human jock high school sophomore? Just think of the bullying from T’odd the Klingon warrior.
Being a Klingon warrior means you never have to show respect or care about your inferiors. But you have to constantly bow and scrape and submit to your superiors, or get your ass kicked if you’re lucky, or end up bleeding to death in the gutter if you’re not. Because in Klingon society, “superior” means “I can kick your ass”.
Well, aren’t you just a killjoy? 
All of the things the OP says are true, and are precisely the reason for the appeal of Klingons. Remember that they are, first and foremost, villains. They’re enemies in TOS, and even in the TNG era, when they’re allies, they’re villains who happen to share some goals with us. And all of the things the OP lists make for great villains.
It also makes them kind of sexy.
Like bad boy bikers. Some chicks dig that kind of stuff. Especially at that age when they get piercings and try to annoy their parents as much as possible.
Or at least I would imagine that it works like that. I am no Trek fan, but maybe you guys could help me out here: Is “Girls don’t like nice guys, they prefer Klingons” a common saying among romantically rejected Starfleet cadets?
Are there any plots that revolve around someone fantasizing about being abducted by Klingons? Any running away with Klingons?
There are no old warriors
at least if you die young in glorious battle you get to go to Sto’vo’kor
You make them sound like ISIS.
Won’t these Klingons be in for a surprise when there’s no afterlife for Klingons anymore than there is for Hu’mons?
is gagh haram?
I feel I should point out that you haven’t experienced Shakespeare until you’ve read him in the original Klingon.