gorgon archer is one of, if not the best defensive creature mainly due to the "slow" traight not hindering ranged creatures as much as melee.
the Hydra is the 5th best creature in a 1v1 fight i have mentioned the maths before in previous posts (behind Earth ele, Sir Corazin, Lord of fire and Steelclaw). but in a real game he lacks viability because of him being slow and an agony magnet. so yes he can be good but it requires constant help from your mage (through teleport, push etc).
both the archer and the hydra give much better position control then actual game winning damage
if you just look at the arcane cards you see there aren't any big cards to damage your mage, which makes sence because nobody really builds a wizard to be a beat down mage with arcane only. he uses the best thing his schools are good at.
arcane: mana control, position control
air: daze/stun lock spells, push control
fire: superior damage over time
water: N/A (so far, wait till necro/druid expansion)
earth: creatures with best offence/defense stat combo (but also slow)
and you know the biggest fact to prove my statements is that the wizard has no 3x spell cost, so the play-testers of mage wars obviously believe that arcane is inferior (slightly) to dark,holy,nature,war and force to warrant say dark+fire to have holy x3 but arcane+fire to have no x3
