Obvious obsequious flattery can be fun once in a while. But I can always get that at certain fine establishments as long as I keep placing fivers under the staff’s garters 
Plain old eagerness to please OTOH is pleasant if sincere, but as hogarth and ** Master Blaster** mention, too much of it can create an imbalance in the interaction and also cause discomfort if the object of the attention knows s/he’s unwilling or unable to reciprocate.
In personal life, the behavior the OP was referring to is borderline creepy. If they’re overly friendly and trying really hard to make me happy, it freaks me out and automatically puts them at a disadvantage. I don’t like to be friends with people who don’t think enough of themselves to meet me on equal terms. If you can’t speak to me as an equal, please don’t try to engage me in conversation at all.
In professional life, like people said up thread, no one likes a kiss-ass. I think that sometimes you do need to grease the wheels by being nice to someone, but only if you’re also being genuine. If what you’re saying isn’t true, they’ll know it and so will everyone around you. Then you’ll be the office suck up.
Go watch Deadwood. Ask yourself: why doesn’t anybody like EB Farnum?
I really hate it when I see people do it to other people besides me. That’s just icky.
The only people I expect to act like waiters are waiters.
We don’t value things that come too easily.
If you go to the store and they’re selling chicken for $1 per pound, your first natural thought will be that something is wrong with this chicken. Even if the chicken looks and smells perfectly fine, you’ll question the quality of the product and take on the assumption that it’s probably inferior to more expensive chicken. Even if you buy it and eat it, you’re be more critical of how it tastes. Get a little bubble gut after eating it? Blame it on that cheapass chicken.
People evaluate each other the same way.
Because it’s fucking creepy dude! My immediate thought is “is this guy coming on to me?”
Unfortunately it is human nature to chase if you run whereas if you chase they run… but then if you don’t chase they may never notice you at all and you can’t run until you’re chased. There’s art to this I hear. :dubious:
I have never been against flattery… ever. I love when people flatter me. I love when people constantly compliment me. 
It makes me feel good about myself.
If you ever go to friend’s exhibition or performance, remember flattery only.
It took me a long time to realize that a lot of the men I dated in Miami may not even have believed what they told me about their goals in life and their notions of marriage: they were merely telling me what they thought I would want to hear.
Turns out what they thought I wanted to hear was a surefire way to make me run away. If they had thought about who I was for a minute, they would have realized that someone with an Engineering degree and who is in graduate school is unlikely to have “homemaker” as her dream job.
My experience with those and other eager-to-please folk is that they start by talking to stereotypes, not to the actual person in front of them. Many of them will change gears in mid-rap if you point out that you lean a different way. Why would I want to be in a relationship (romantic or otherwise) with somene who, rather than showing himself to me, tries to play “mirror, mirror on the wall”? Why would I want to have a relationship that’s based on a huge lie?
Your own definition of ingratiating is “an eagerness to please and pursuing intimacy prematurely” – that’s the answer right there.
It has nothing to do with “treating people like shit.” People like to be around their equals. What is the benefit for me to hang around someone less intelligent, less sophisticated, or less capable than me? Sure, elevating others out is fun at first and can give you a bit of an ego boost. But eventually, they come to resent that help as much as the other person resents having to give it all the time.
Note the word “some” in my post.