If you're going to place restrictions in how you play on yourself based on then eventually you will miss out on something. If you really can't bring yourself to do any OOC activity in this game then as said, your only option is to make a character for whom the multi-disciplinary approach is in character. There's some potentially interesting concepts down that road.
You're also assuming this is the proper ending to the role quests that none of them will be complete without. There's good odds it's just a couple of cutscenes to give you a pat on the back and then dole out whatever reward comes attached to it. It may end up having the same amount of story impact as the quests for collecting all the primal mount drops, which add a bit of lore on those mounts but aren't required for a full appreciation of the content that unlocks them.