As much as I'd enjoy Zenyatta buffs I also can't deny that I'm very effective on him. I just don't use him all the time. You'd have to be a masochist to use him on King of the Hill as a solo support, that's Lucio's domain.
On offense I only use him behind Reinhardt's shield, otherwise I stick to using him on defense. Yeah, Widowmaker can bodyshot him if he has no builder armor or shields - but they need to have a line of sight on you first. I am an average Widow and I have no trouble deleting Mercy if I'm unchallenged by another sniper, she usually has to put herself in harm's way to heal or rez. On Zenyatta, I try to never give snipers the chance. I generally need to be flanked or I will sit back and heal my team from safety. And Zenyatta vs Genji/Reaper/Tracer goes in my favor more often than you'd think, because I am watching/listening for them and when I'm on Zenyatta I am as skittish as a squirrel on coke.
I typically play him in conjunction with a Torbjorn friend and he brings armor to me ASAP. We have a very high winrate on defense using this method.
His ult is so situational that even if it built faster I'd probably still hold on to it a lot. But I've saved so many last minute capture points with the thing that it'd threaten to become game breaking if it charged as fast as Mercy's rez.
I catch shit sometimes for picking him so if for no other reason than public opinion I'd like to see him get some buffs. But if they come with tradeoffs to his offense then no thanks, I'm good.
I really need to work on my accuracy.
(PS4)
Accuracy is such a pointless stat in a game with infinite ammo, unless we're talking Widowmaker or something.
On Lucio in particular I am spamming nonstop. I tag so many people around corners and finish off tons of Tracers trying to back off. I shoot at snipers to throw off their aim and force them to move, stuff like that. Just shooting at everything constantly.