I understand, and to a certain extent I agree, but there are different "playstyles" in the different jobs (less in FFXI than some other MMOs, but they are still there), and people can become attached to how they play. I think there is a difference between how people play a class effectively (personal playstyle) and how different classes play (class playstyle). It's the same when people prefer to nuke in the back instead of swing in the front. It's all numbers and a dead monster in the end, but I'm sure people have fun doing it in different ways.
I also beg to ask why SE bothered to make said job if I wasn't going to be able to do anything with it when it's leveled. I mean, how am I supposed to know at level 20 that the job I'm leveling is going to be useless at 75, especially a new job that hasn't been fully updated with merit abilities and such? Why was it so naive to think they would eventually fix the jobs to be acceptable? I mean, as useless as my PUP was at 75, I curbstomped everything in Y. Jungle in the late 20s, outdamaging every person on every class that would dare to parse me by a WIDE margin (except other PUPs). Several PUPs will give you the same story of amazing lowbie numbers. Yet I'm sure lolPUP is still a meme with reference to endgame content, and after everything I attempted to do with the job I agree with it on a lot of accounts. Why was that ok with SE? Not to mention that there have been several times the status quo has been reset. 2handupdate, remember?
That's why I'm so curious with 14 right now. I really want to see what they learned from 11 with regards to class balancing and player/GM interaction. I agree with Kaylia when I say this is more of an SE problem than a player problem, even though they are both responsible. You can't really blame a player for not wanting to invite a job when SE doesn't give them much of a reason to. Hell, SE often gives the player reasons NOT to invite a non-cookie cutter job. It's a shame.