Many fans of The Elder Scrolls feel that the series has been progressively "dumbed down" since the glory days of Daggerfall and/or Morrowind. While I won't start that debate here I have noticed a steady decline in spell effects since Morrowind.

http://www.uesp.net/wiki/Lore:Magic#Spellcasting (click on each school for a comparison chart)

I find it rather sad that in a world so infused with magicka as Nirn, not only is the variety of magicka decreasing, we also lost the ability to experiment with it (via spellmaking). Mages and magicka based races (Altmer/Bretons) are some of my favorite aspects of the series, and the erosion of the spell system really hurts them. Lets hope that the next Elder Scrolls game brings back some of the cut spell effects, adds some more, and revitalizes spellmaking.