No? In Morrowind, High elves had the highest max magicka multplier, followed by Bretons. Which means they had more starting magicka than anyone, and could boost their max magicka far higher than anyone with fortify intelligence enchants. In both MW and OB, Bretons were near imm7une to all magic. It took one lucky drop in onblivion (Mundane ring) and Bretons were untouchable by magic. In MW, a Breton with the saviour's hide could wear Boots of Speed with impunity. Let's not forget the fact that beast races were barred from one clothing item.
No in Skyrim the races have been pretty much levelled out. That being said, magic users will enjoy definitive advantage with Altmer. Any player will be better off with a Breton because they will be that much closer to to magic resist 85%, and Nord/Dunmer come in at a solid 2nd place for their immunities. Orcs probably have the only useful once a day ability.
What really god nerfed in Skyrim is birth signs.
Yea, in Morrowind Bretons had a very minor Fortify Magicka multiplier, and a very minor increased starting Intelligence, which gave a higher magicka off the bat, but was a bonus that was very easily made up with any other race that put a focus on Intelligence and had any kind of Fortify Magicka effects.
Altmer had more of a multiplier, but that still exists with their +50 to starting magicka.
You say Bretons were very good against magicka attacks, and they still are with their magic resistance and their Dragonskin ability which absorbs magical attacks. This hasn't changed.
And how did birthsigns get nerfed when the same exact concept applies with the standing stones?