I think that the magic seems weaker because of the work that is required to make the lowly battlemage. Think of it, is it easier to build a barracks and produce archers for life or have to make a new initiate for every battlemage. Then if you want an archmage, you gotta morph again. Of course, that's why magic is an advanced faction. The other problem is that the units such as the behemoth have horrible movement due mainly to their size. Glest has trouble navigating larger units.
I've figured out why Magic always loses to Tech.
Magic doesn't always lose to tech if the player is good enough. A recent game of mine had me building up a golem and battlemage defense, then sending a wave of archmages and dragons at the foe right after the attack. Utter pawnage!
I still think that the game is balanced, there's just those annoying bugs like missing lots, and the fact it is harder to play magic if you do not know how.