I think that casting the touch spells accounts for a large number of spellcraft improvements. Are there any thoughts to retain this aspect or is it planned that the increased rate of improvement of the touch spells make up for it?

Spellcraft can still go up on each casting normally. As an invoker, you'll probably be casting enough other spells at low levels that the easier time with the touch spells won't impact it much. If it does, and you really care, you can spam pretty much any other spell.

valguarnera@carrionfields.com