Why is having Strength 1 so bad for the Sprite? The Troll has a Craft 1 and you don't see anyone complaining about him...
Well you have more chance of battle then psychic combat when encountering other characters who will kill you off if you've only got one strength.
I guess the other thing is that (in the past anyway) you were more likely to come across a high level strength character than craft. If I recall correctly in the 2nd Edition, there were 3 dragons you couldn't beat in strength but one ghoul type character of craft 10 or 12. Either way, the odds seem to indicate more strength battles on the main board starting out.
Warhorses came later and you still need to be able to draw the card or afford it.