I don't see how people say the magic system was overpowered in Oblivion.
Sure you could create really powerful spells, but with the level scaling those weren't enough. I had to create custom spells with really long durations and weakness to magicka just to kill everything at level 50. As a high level mage I got mauled far too much. The only issues I recall were the 1 second fortify spells. But conversations are in real time, menu's can be too. That fixes those exploits. If all else fails, make spells cost more magicka. Removing the spellmaking isn't the only solution, nor is it the most rational.
Not sure I've ever heard anyone accuse Oblivion's magic system as overpowered, I don't even know why you would even bring that up but oh well. The thing is that with the new magic system, spell creation and dual wielding spells which have 7 combinations just by itself could easily get out of hand. So if BGS decides they aren't going to put it in then fine, because the new spell system has more combinations then the old spellcrafting system does. They aren't trying to "solve" anything by removing spellmaking, they changed the magic system to make it more dynamic and the changes may warrant not putting the spellmaking system back in because the new magic system is a good replacement.
Quit assuming this is about nostolgia. That is every Oblivion lovers fight against anyone who liked Morrowind. Maybe some people actually prefer customization over premade spells.
Firstly, I'm not an Oblivion lover, I'm a TES lover whose favorite game is Daggerfall. I'll defend Oblivion when people go on about how Morrowind was perfect and Oblivion was so bad. It is nostalgia when people refuse to accept a new system over their old system even if the new system may do the exact same thing as the old system and have more options for customization, which the same people that refuse to accept the new system always say is their most important aspect in their mind.