No. Sorry, but that is a horrible idea. There is a very popular MMO out there that did just that and every single class lost its class identity.
So go out there, level a class that can do what you need, and get over it. Cross-class actions work perfectly as they are and I hope they won't mess with that. Every job feels unique that way.
They are great because a) character development b) getting you to play the game and try other classes/jobs (so you learn more about what others might play, what a crazy thing, huh?!) c) rewards for effort d) class/job identity