Absolutely.  The ability to give specific magical spells to various units is really critical.  I know the designers were trying to keep magic special (as in, only heroes wield magic), but a specific spell, researched as part of the magic tree and unlocked as an "item" placed on units (at a high materials cost, or even a high crystal cost for manufacture) so that we can have priests, wizards, warlocks, etc. on the battlefield is really critical. It may be that SD is waiting until they can implement unit abilities more fully before they go down this path, but I totally agree.

I sorta agree. I don't think that they should be casting spells everywhere, because that's what channelers are for. However allowing units to cast 1 or 2 spells would make the combat more interesting. So you could say build paladins that can heal or units that use items to shoot fire darts. This is actually probably pretty easy to mod. There are however many other things that should probably be added first. Like more armor and weapons, intelligence items like robes for troops, a paper-rock-scissors dmg system etc.

edit: Lol, was just thinking about tying magic granting items to shards. So that you needed a fire shard to get fire items etc. What would the other shards do? Storm! Grasp of winter would be really annoying....