Personally I say that "bolt" should be +0 damage, same as "arrows" now are +0 damage. After all, "arrow" and "bolts" should be the NORMAL ammunition, and only stuff that are BETTER or WORSE should have any change. Like Bodkin is +6 and steel bolts are +6. And bent/rusty/whatever is -1/2/3 or whatever. It just makes more sense.
I also think they increased the damage of the crossbows/bows, but if you say they only did that on the top end, then that's a bit unfair. Then again it's not like we get THAT much info from the devs when a new release comes out. I'm happy if they even say "items values were changed".