- Fix runes.
Runes are far easier to buy or trade for than to find in a drop. Over 4 years, my best drop was an ohm, but 30 minutes with ATMA (a muling application) and handful of runes and I had all the runes.
Single player makes things a lot easier.
- Either fix set items or add a bunch of new ones. Again, the average player will never complete a set that’s worth anything. It’s just so random and hard.
I dunno, I’ve finished every set at least once. By the time I quit, I was only mf’ing for a few .10 items, like Mang’s Song and Tomb Reaver.
- Fix Nihlathak.
I really need to post my Nithalak killer build. I never die to him. I hunted him a lot in .09 since it was far faster to get a lvl 97 charm for rolling from him than from Baal. In a nutshell, build a Meteor/Orb sorc with max block, and hide behind one of the pillars. The pillars force the mobs to attack you only one by one (and with max block, they can’t touch you,) and the pillar protects you from direct attacks. If you don’t kill any mobs, he can’t use corpse explosion.
- Completely overhaul looting system.
I also made a Baal mf’er. I can do a solo baal run in under 5 minutes. Make a lightning sorc (doesn’t really matter which spell you pick, lightning or chain lightning both work fine). Lister’s group is the only one that can possibly spawn lightning immune, if he is, restart or lure him south. If he’s not, tp’ing around the throne makes them stuck. Then, kill baal using a 4 ist shield with hint #1 above. 
- But in hardcore, pickup groups are just too risky as is.
Play single player and learn the joys of Players /X. 
- Trapsins need an end-game build
Never played em.
But, I think, based on my lightning sorc builds, theoretically, a a lightning sentry build should be able to solo the game (skipping lightning immunes, of course.) I’m not sure if you played with synergies, but everybody got beefed up.
- So do bowazons that don’t rock a Windforce
Best bows in the game now are the new 4 socket runewords for bows, and they aren’t hard to get. 4 socket mat bows with +3 bow skills are all the rage, far cheaper than breath of the dying in a hydra bow, and without the skills.
- Tone down the immunities. Yeah, I get it. Pre 1.10, DII was too easy. But layering multiple immunities on nearly every mob in hell is just stupid.
You usually do have three types of damage, don’t forget the merc. Usually, I played a sorc with a merc, and tp’d past 80% of the game.
I never tried the hidden bosses (I was 100% into Single player by then,) but I heard that was pretty bad too.
- Bring back gambling uniques and sets. They shouldn’t have made these so rare (again, literal lottery odds). They have a good method now for getting SOJs out of the economy, let us gamble for uniques and set items again.
I never had much trouble getting a meph runner up and running starting from scratch (always a blizz sorc.) The last time, I had an entire mule account filed in 3 days.
- Buff gems. Past normal diff, the only use of gems is a few middling cube recipes. Gems are a good and neat idea, make them useful into Nightmare at least.
I think the cube recipes are great, and they did bring some balance to the gems in .10, e.g. clearing sockets, adding sockets, etc.
But, the old recipes are still awesome. Rolling lvl 97-99 charms was awesome (3 pgems.) And theoretically, 3 socket magic swords are now priceless.
- US EAST such shit.
Heh no argument there, I used to go there when USWest was down and taunt the easties. :()
- Ease up on the inactive character deletion.
Ah, the joys of single player. 
- Figure out a ladder system that gives the average player a chance to see their name.
No opinion here.
- Come up with a proper PvP system.
No opinion here either, although I made a fortune in sojs crafting PvP equipment. I was a crafted glove salesman. 
- Give us real PVP by bringing player damage, player hp and monster hp closer to a balance.
PVP has always been screwed, even back in the day of the Pink Rabbit’s belt, white items, and Order Noose.
- Wow, this turned into a real DII rant. I’d love to play the game again.
I never thought I would get tired of D2, but about 6 months after starting single player, I had built every single possible build I wanted to play, tried all the equipment, and achieved every goal. I was sitting there one day, rerolling meph levels trying to get the stairs closer together for my mf run, and I realized, I’ve done everything I could, it’s over.