Might be awkward? I foresee it rapidly becoming a major nuisance. Having to reconfigure the hotbars every five minutes passes well into the realm of tedium, and that's not something you ever want to see in a game.
i see your point, but i think that's a bit exaggerated.
if we stumble upon dark roads entrance, we should expect darkspawn, where is darkspawn there should be at least one or more nasty emissaries (hated those guys, crushing prison and other nasty stuff) - knowing that, i pick a Smite (knowing it will be useless against Carta or golems) and put it in the 'just in case' free slot.
if i venture into undead infested ruins, i know there will be skeletons.. so my cold magicks would be useless, but i want to balance it somehow - put one cold spell, preferably some cc or high damage one into 'just in case' free slot.
i don't know bestiary (wink-wink, a well-timed info release maybe?), have some vague idea how does it look. we don't know the level design (and i don't expect BW to show us all locations and mobs positioning; outside the actuall game)
the problem lies somewhere else, well at least for me. i cannot ditch the party, i cannot roam the ruins myself - a mage alone? with 8 abilities? with cooldowns? no healing spells and 8 potions? i mean, come on!
i don't want to play this game on easy/normal, i feel most of ppl in this thread don't want to do that either... because it's no fun