What is wrong with a wheelchair ramp? As far as a mentally disabled person, obviously if he doesn’t have din Shotah, in which case he would not be obligated in mitzvos, whatever can be heard clearly is fine. The Shulchan Aruch writes that one who is blind may daven before the Amud (though may not be baal kriyah); certainly this is no different. Inclusive just means that if we can, we go through the bother of helping someone whom these simple tasks are more difficult for. That’s all.
May don’t want to be bothered. But if it’s in the realm of Halacha without sacrificing Kavod HaTzibbur – why not?