The OP makes a pretty good argument, I'll give him that, but Kazrah pretty much hit the nail on the head with this entire post as to why I wouldn't support such a system.
+1 for him
Talents, like the attribute points that recently went the way of the dinosaurs, are largely nothing more than the illusion of choice. The vast majority of players will simply google the "best" build and copy and paste that onto their character. Anything else and you are hindering yourself for the sake of being different and, by extension, hindering whatever party you join for group content. I'm perfectly aware that not every player (myself included) plays 100% optimally 100% of the time and I would never expect them to but, depending on how more or less balanced talents are, picking a sub-optimal option is shooting yourself in the foot before you even step into a dungeon or trial. Like not melding your gear or bothering to invest in food or potions- sure you can probably still succeed without it, but it would certainly be easier and increase your chances for success to do so with.
It also opens up the door to the type of elitism where people who use the "best" builds exclude (or worse, harass) those who do not. This is attitude is already pretty rampant in the game already in regards toward optimal classes in each role and which gear and melds they use. I would like to think that we as a playerbase could rise above it, but my above examples have already proven that patently false. A "This is why we can't have nice things." kind of argument.
In a perfect world, where they actually manage to perfectly balance all of the talents across all of the jobs, I would be less opposed to a talent system. Sadly, I have never once seen that happen in any of the various MMOs I have played over the years. I'm not saying it's impossible, but I'm not going to hold my breath, either. Often times, when devs have managed to bring them within a reasonable margin of each other, the end product talents are either so homogeneous or have so little influence over actual play that there really is no point to them when all is said and done.
In the end, I would rather the devs work trying to achieve better balance between the jobs as they are now and smooth out the leveling process for them than throw the whole system into chaos by trying to overhaul it (again) with the addition of talents. People are citing WoW as an example of a good talent system (which as an old WoW player, is actually pretty hilarious to me) but it took Blizz years of reworking and polishing their system to approach anything even resembling balance. I shudder to imagine the hot mess that FF14 would be if they tried to shoe-horn talents onto our jobs at this stage in the game.
TL;DR-
I don't think talents are inherently bad but I have absolutely no faith whatsoever in the devs being able to make meaningful talent choices that are perfectly (or even reasonably) balanced across all the jobs and therefore can't support taking resources from other aspects of development or throwing the game into disarray for however many years of developing, reworking, and polishing it may take them to get it even decent, let alone "right."