When MC-13 was fixed, it was specifically only fixed for players, as some other mobs had scaling issues with arrows rendering stuck inside of them. However, a large number of mobs did not actually have scaling issues, and yet arrows still stick inside of them. It should probably be reenabled for more specific mobs which do not have this problem in modern versions.

Ghasts are the only mob I could completely confirm to be affected by scaling during Beta 1.8-1.8.1. Slimes likely were as well but I never managed to get any to spawn.

Likely affected mobs that shouldn't render arrows:

• mobs with baby variants
• slime/magma cube/phantom sizes

This may be a feature request, not fully sure