In all fairness, Kefka's face wouldn't sell as well.
Also, Materia was about more then just stats, much more. They primarily added abilities, spells, or summons, and also happened to increase the stats that supported said new powers.
Magicite was, especially on the surface, mostly about summoning, granted. Yet each Magicite also increased a particular stat for the character it was equipped on if they leveled up with it on. Handled from early enough, you could create quite the buffed up characters, to the point where the Summons actually took a backseat.
Hence why I'm curious to see what, exactly, the system in XIV can do.