Are you even reading my posts? Where did I say spell vamp being core was the problem? The problem is it was completely essential to some champions, and if it was weak they were weak. When spell vamp was strong, other characters abused it, resulting in a loop of nerf buff nerf buff and it was balance hell.
The issue isn't here anymore since Gunblade is a mixed item with only (15% ?) healing on abilities. Now very select characters can afford to build it, and most of them dont do it for the spellvamp, but for the burst and mixed stats.