The Warrior job was designed as a tank. For them to queue as a DPS, they would need a kit overhaul, or rather a different, secondary kit for DPS. If they do this for Warrior, then they must do this for other classes as well, meaning a whole bunch of alternate kits to be designed, balanced, tested, etc. What you are asking for is no small feat and doesn't fit with the game's design. Instead of playing one class with a few 'specialization' options, you get to play all the classes, each with their own set role. Such is the class/job system in FFXIV.

I'm also wondering how it is that you've ran into so many horrible/rude groups that treat you so poorly when I've yet to see a single instance of such behavior in the 2+ months I've been playing since I returned to this game. I'm not saying these things don't happen, I just doubt they happen at the frequency that is being suggested in this post.