I remember Blue Mages quite well as having some of the most interesting stuff in pretty much all the games they were in. Yes, like most any mage by the end of the game you had some obscenely overpower summon, or physical attacker that could beat them, but again, that was true of any mage type.
In FF-VII I never once used white/black for anything other than to see the effect. I used enemy skill almost exclusively for any support spells I needed, and items for anything else. Next to maybe Knights of the Round, ES was my most used materia in the game.
FF-VIII I junctioned all my magic and never used any of it, again relying on items for any curing I needed. I think the only magic I ever used to aura to put my gunner guy into limit break in the final battle so I could spam pulse ammo. Unfortunately blue magic was only available in limits in this game so it was under used by me, although I made good use of it when I could.
FF-X was a tiny bit more balanced as at least I used LuLu thru about the first 1/2 or so, but past that it was pretty much Auron and Wakka all the way, especially after they got their break damage limit ultimate which were insanely overpowered. Blue magic was weak in this one, nothing overly exciting, especially in comparison to the melee who had insane power, but same was pretty true of the summoner, thf, blm too.
Right now I'm messing with FF-X-2, and here melee is again quite strong, but the gun-mage is still quite useful. Absorb a nice easy bit of damage and restoration for early game, and although I doubt we'll see this, the 4X damage of the fiend hunting skill is very handy at times.
So, as you can see, pretty much all magic types seemed unpowered in general to the physical stuff, the pretty much opposite of what we have in FF-XI where the magic remains very useful till the level cap, in many cases vital (no having 99 mega-potions in this game to replace that whm). However, despite being a mage-type, blue magic actually often still had it's strong selling points. FF-VIII had one of the few attacks that could break the damage limit. FF-VII had awesome support potential, and some good offensive stuff too.
In this game too it has some strong possibilities to play many a role, from DD to debuffer, not to mention bring some more variety to the mage ranks. I want to see some other jobs too, but BLU is definitely a good start in my book.