i dont know about everyone. but after a few years of playing 3.x everyone in my group had figured out that you needed some kind of spell casting ability by level 10. and that full on casters had better/more option available. and we went on a short run arms race with eachother. after we got that out of our systems we all tried to pull back on how crazy we got with characters. we also spend more time in roleplaying senerios and less time in combat. at times we end up with characters spending sessions building castles/cities and or working on special projects like creating a masterpiece weapon or armor. things like that. we also tried to work with the DM so we knew how far he was willing to let us push the limits of what a character did, or how far we could go with a concept without breaking things down.
This. Casters per se are not the problem (unless not until really high level or if you really want to break the game in half) but rather the disparity of power in a group that includes both casters and non-casters. Also, talking to your DM about powerful characters is vital IMHO (I always approach mine with every optimized char concept 'I want to play a char that will do this and this, are you cool with it?'). Brining a DM or your fellow players out of their 'confort zone' regarding power level usually leads to unfun games.
When I started playing D&D with my first group (all new players except for the DM), I was the first to realise the power of casters over non-casters and start developing optimzied builds . The DM (who was a retard in retrospect) never tried to talk with me about it. Instead he just decided to call me a munchkin and kick me out. Later I met the group he got kicked out of (I still play with most of them today) and found out he was a failed optimzier himself. He tried to optimize for a few months, faild horrible in all of his builds, then decided to start an anti-optimization campaign, based around 'If I can't be strong, then nobody should').
The campaign I currently play in is probably the pinnacle of optimization my group will ever do. We all play (nearly) full casters (Wizard/Incantatrix; tiefling wizard/eldritch knight/abjurant champion, DMM Persist cleric/ordained champion, ardent/cleric/psychic theurge, bard going for sublime chord, and we might get a druid joining us in a few sessions) and having tons of fun. I play the wizard, and I really don't think there is much more practical optimization I can do on him. We've talked amongst ourselves, and after this campaign is done (about 1 year or so) we'd all like to do a low powered one, to try out all the fun builds we thought about over the years, but didn't quite cut it power-wise at the level we usually play.