Actually quite a few skills in mage and ranger trees would do same or even less damage than bow, staff or dw wand attack if they have aoe or high utility. Plus crippling strike has insanely high damage modifier anyway even compared to other warfare skills. Both of these skills have AoE, CC and battering ram is a mobility skill which is also quite cheap. They don't deserve high damage modifiers. Exact numbers are debatable.
If they don't deserve damage modifiers they don't deserve increased AP costs. If two handed skills cost +1 AP like you suggested AND these skills didn't have damage modifiers I would only use basic attacks, because it would be more efficient.
