What I would like to see most is a big clean-up/sprucing up of the old content, particularly on hero side. A big trimming of the endless "Defeat XX [group] in [zone]" missions and the pointless "go touch random boxes patrol the city" quests from contacts on hero-side is my main issue, and it's one of the big reasons I prefer villain-side to hero. When you play the newer content from post 2008 and then go play the old content... the age really shows.
My suggestions would be to limit these contacts to their story arcs, and delegate the street-sweeps and one-off missions to the security chiefs, similar to how it works in Praetoria and the Ward zones. And while we're at it, keep the missions in the same zones. Always annoying to have a contact in Skyway who sends me on a mission to go talk to a guy in Atlas, who then tells me to go to Steel and after that go to Perez, then head back to Skyway to turn it all in.
On that note, I'd also really like something to do in the hazard zones that have always been completely barren. Obviously I don't expect an unpaid volunteer team to give every hazard zone the same treatment that Faultline or the Rikti Crash Site received, but it'd be nice to have some incentive to go into these zones other than exploration badges. Maybe have some kind of daily/weekly event in these areas, having players clear street mobs until a boss appears, with merits/temporary powers as rewards.
And just so I can end this post on a positive note and not sound like I'm being whiny or entitled, I do want to give a tremendous "thank you" to the folks who brought this game back after so many years and help keep it running. There truly isn't any other MMO like CoH on the market today, at least none that I've enjoyed, and being able to come back after so long has made me very, very happy. Thank you!