I always seem to learn something new with D&D. So according to Touch Attacks listed in both the d20 SRD and the Pathfinder SRD, it appears touch attacks ONLY ignore armor, shield, and natural armor and they do not ignore Dexterity, Dodge, Deflection and any other (such as Insight, Luck, etc.).
This I did not know, I always assumed it was just Dexterity, Dodge, Deflection, and Unnamed bonuses. What sealed it was that some monsters from WotC books seemed to also follow this trend with their Touch AC, as I've never seen an Insight or Luck bonus applied to Touch AC in either monster of NPC statistics (it's possible I really never noticed, though).
So is it true that all modifiers apply to Touch AC except armor, shield, and natural? It seems that way according to the wording. Thanks.
Well, if you think about it, if you get missed a lot out of pure luck, it makes sense that it applies no matter what.
Significantly, note the Magic Item pricing for 'other' AC sources (luck, sacred, insight, etc.); they are all bonus^2 x 2500, significantly more than regular AC, and a bit more than Deflection, even.