I still don't know why they removed spellmaking. It's like Todd doesn't trust the player to have fun in any ways not explicitly sanctioned by Bethesda.
Too complicated for a majority of console gamers (Note: I said majority. I don't consider B12r's to be the majority.)
I don't really know if complication is the issue, as intuitiveness doesn't always preclude depth. Look at what Skyrim did with enchanting: removing the ridiculous cost and failure rate was what made the skill far more usable to new players. It is more hindered by the small number of enchantments available, individual item restrictions, and the lack of conditions (i.e. no CE on weapons, no cast when struck on armors), which are features that would not affect the inherent intuitiveness. Inexperienced players would likely stick to CE armors and +element weapons, but experienced players could have the complexity of Morrowind's system (say, an armor that provides fire resistance and explodes in an AOE fireball when struck, or one with constant bound summons).
I'm guessing the main reason for removal of spell crafting is to limit the infinity + 1 nuke spells, or prevention of abuse related to certain spell effects. Also, in the interests of making things look pretty, all spells have their very own effects, and having to code and animate combined effects, especially for destruction spells, is probably a bit of content cut due to the 11/11/11 release date.
From my experience, most of the broken spell effects in Morrowind/Oblivion are things you wouldn't notice on your first playthrough (or at least my first playthrough). I wouldn't think most people would intuit to cast levitate on their enemies, and even then that could be fixed fairly easily (levitation restricted to self, enemies are immune to levitation). Finally, if the time the player has enough mana to cast the really crazy nuke spells, he's probably powerful enough that it'd be more immersion breaking if he
couldn't fly over Vvardenfell wiping cities off the map.
They changed spells from simply being a projectile with a damage type to a unique set of effects. What kind of spell could you design that wouldn't be basically the same as an existing spell or a combination of some others?
If we look at the destruction spells, we see three spell effects (fire damage, ice damage, and lightning damage), and several different conditions (channeled cone, ranged, ranged AOE, rune, wall, non-ranged AOE, and chain). Worse still, conjuration, illusion, and alteration have gained no new effects from this switch to "unique" spells. Furthermore, several spells in each of these schools are the same spell with the effect numbers increased (ironically, this was Bethesda's justification for removing spellmaking). Thus, the only thing that Skyrim has added to destruction magic are four new conditions (channeled cone, rune, wall, and chain). The spells can still be sorted into the Morrowind/Oblivion spellmaking model of effect + condition, and thus could easily be generalized into the spellmaking system. While the small number of effects means that spellmaking would be a shadow of its former glory, it would still go a long way towards allowing players to make up for Bethesda's mistakes, such as scaling up the channeled cone destruction effects to make them useful past the first few levels, averting the "padded sumo" gameplay that plagues that late levels, or make up new effect + condition combos (how about a paralyze rune?).