Galka make some of the *best* mages. Not due to stats, but due to learning how to properly manage MP, and use their spells at the correct times. Also, we're not wet paper bags early on like most other race's mages.
And for the record, overall I think that Galka exceed the other races in WAR, PLD, BST, NIN, MNK, and DRK (Maybe even WHM). Galka has above average STR and no detriment to DEX, which allows for the most effective DD in the game. Elvaan sacrifice native acc and crit rate for their high STR.
RDM and BLM are hard to play as a Galka simply due to our worst stat being INT. INT is one of the few stats that is highly important when calculating resist and damage rates. For the most part other stats can be jacked up so much by gear, that you'll cap out, but INT is hard to do so with, at least as far as I know.
Also, for what it's worth, I was just in the dunes as a BLM15 in a pt with a Mithra DRK15. She had about 20 LESS HP than me, in addition to much less MP. It just made me giggle about how the racial divide in HP...