I was going to post this in another topic, but I'm sure it would have just totally hijacked everything.
Anyway!
Yes, anyone can play how you want. Whatever will make you enjoy the game the most is totally up to you.
However, if a party leader disagrees with the choice you are making, it is my opinion that the party leader is ethically correct to boot you. There doesn't have to be a big fuss about being booted. It's nothing personal.. it's just "business."
Playing solo how you like is one thing, but playing in an experience party is another. You are not only affecting your own experience, but 5 others' experience points as well. I don't know about anyone else, but I value my time, a lot. If my time during an experience points grind can be reduced at all from a changed subjob, or a change playstyle, then I'm going to make sure it all happens.
If you don't have the cookie-cutter combos, and you don't play the traditional way jobs are played, I don't think you should expect everyone else to appreciate your theory. I don't think you should be surprised or upset if anyone ever boots you from a party.
Take, for example (this never actually happened), I invite a level 57 RDM/WHM into my party. We're fighting Goblins in Gustav. I notice that during the battle, the RDM starts to cast enthunder and begins to melee, even before he was finished with his debuffs and refresh cycle.
There was no way I could really find this information out before I invited him. I politely ask him not to melee. He says "well it's not fun to just sit there and cast." I say "well, you are wasting valuable healing MP from our WHM with the AoE, and you are not focusing on the role that I brought you here for." He says "well, this is the way I have fun in this game. I am sorry, but I will not change my playing style." I say "Ok, fair enough. However, that is unacceptable in my party. There are probably other parties that will allow this." He SHOULD say: "I understand. No hard feelings."
I know, of course, a conversation would NOT go that smoothly =)
I bet it would be more like "**** you, Chops. You don't know ****, you n000b. My enthudnar duz 1337 dmg and everyone needz a RDM in they're group!"
Summary:
Play how you want, but don't be surprised if people disagree with it during experience parties, and would like to replace you with someone that will do your job the way the party leader wants you to.