I have to agree with this. Elemental damage just became VASTLY more important, but the protection is lagging.
There are only two 5* shields that provide any elemental protection at all, and one of them (the dragon scale shield) lacks normal defense. That really does constrain strategic options. The larger issue is that by limiting each armor to only 2 types of defense- while mixing 4 types of damage into levels- players are forced into a very limited set of gear choices, or else they are forced to play the game of "which new supermonster is slightly less likely to kill me". Limiting damage even when you lack defense attempts to keep this from being a problem... but by doing so, it renders defense less important.
Also, a related complaint: there is currently a game mechanic whereby big hits don't kill you instantly, but rather leave you with 1 bar of health left. However, the new mecha-knight beam weapons can strip you of almost all your health, AND inflict shock (a damaging status condition) at the same time.... meaning that half a second later, the status condition kills you anyway. This seems to go against the spirit of existing game mechanics. I suggest that if an attack has already taken out your health, it should not be able to inflict a paralyzing, unblockable, and shield-disabling status condition as well.
Well it's good to have some numbers on here, but it's something I've been saying for a while.
I actually made some suggestions on how it could change: http://forums.spiralknights.com/node/711
Admittedly, that was quite a few balance patches ago, but still...
The basic system is there.