Enjoy the game in any way you like, there is nothing wrong with favoring dps, I have friends who don't find themselves as dps and prefer tanking or healing. I started as smn and it's my favorite job and will always be, I have had the chance to enjoy every job till I got them all to 60 and till now I find myself going back to my main. The fact that you are concerned about switching jobs makes you among those who give an effort with other jobs especially in classes like tanks and healers and that's what makes a good one.