The lack of features, that were in previous games

*Cough Spell making*
Been mentioned before.
In Oblivion,spells had limited visual effects,simply the colour and sound the spell made.
In Skyrim the effects are much more varied and complex.
And Oblivion's spellmaking was simple as hell.
Range,power and area of effect.Thats it.
You had ranged spells and on touch spells.
Skyrim's magic system would make it much more difficult to put in spellmaking.
Constant stream spells,blasts,over time effects,spikes,name it.
You'd have to put in all those possibilities,and while it would be awesome to be able to make a Lightning Spike that does damage over time and has an impact on hit,it would be very,very hard to make it work properly.
And i'd rather have a properly fleshed out spellmaking system than the beta version we got in Oblivion.