I understand you frustration. I don't have nearly enough splat books to be a true optimizer but even just the fact that I built a conjuration-specalized wizard with a controller focus and batman capabilities puts me miles ahead of the group. We're in Ravenloft. Every session my wizard with his 30 AC (5th level!) runs out on front line and tanks. Every battle, I am the one who doesn't need healing (I might need to re-cast False Life but that's it). But these numbers may as well not exist. The cleric chides me ever turn, the rogue won't settle down until I read off my AC to him, etc. The fighter has learned to let me be because I give him an Enlarge Person or Haste every time he wants it.

My favourite is that the rogue jealously guards the privelege of opening doors or chests or walking first into new rooms. It doesn't matter that I'm immune to fire, immune to missile weapons, can absorb cold damage, have higher saves than him and just as good an AC; it would be a disaster in his mind to let the squishy wizard spring a trap. He also is not a fan of me using invisibility to come along on scouting runs (I partly understand that one because I might still make noise with less Stealth ranks than he has.)

However I try to stick to the roll of buffing the others and that earns me a lot of props. They are getting used to this wizard who does more than Fireball and can fit in anywhere there is a need. Like you said for your group it is a grudging acceptance, where they may not like it but then they're asking for build advice.

One thing I will say though is not to let it offend you that they don't take your build advice when you are GMing. Sure your point about Stand Still and Combat Reflexes was spot-on but there is something weird about taking the advice of the guy who is trying to kill you. Ultimately they have to make a team that works well as unit and that might be better serviced by the trust they show by taking each other's advice and having a shared idea of what a good build is. More fun to die together than to win while resenting each other, basically. In general I try to bite my tongue and not give build advice when I am GMing, though sometimes I can't help myself....