True, Nords don't care for magic (for the most part) and this wouldn't care for making their own spells. In oblivion, spell making was completely restricted to members of the Arcane University, which no longer exists. Also the Thalmor's sack of the imperial city could have destroyed much of the university.
Well how about making Nords the only playable race then, since you are supposedly confined to Nord sensibilities when it comes to magic. But, then again... you mention the Thalmor... did the Thalmor destroy their own spellmaking abilities and confine themselves to Nord views of magic as well?
The lack of Spellmaking and he loss of spells is completely without basis in lore and it is silly to suggest otherwise.
The magic system svcks... missing many spells, destruction is useless to the point of frustration and spellmaking could of hid many of the flaws.