The game still targets the selected mob (entity) during the short death animation so does not allow other entities or blocks behind to be hit.
Steps to reproduce.
1. Equip weapon of choice.
2. Kill mob
3. During death animation, try to hit/access things directly behind where the mob was standing - not possible
I would personally prefer to see the hotbox completely disappear just as the death anim starts 🙂
Linked issues
is duplicated by 1
relates to 4
Attachments
Comments 12
Still a concern in 1.7.4, 1.7.5, 14w08a and 14w10c
A pretty annoying bug indeed, especially when fighting a big group of mobs. Still present in 11b.
Confirmed for 14w21b.

Confirmed for 14w25b
Probably also with players!?

Confirmed for 1.8.1. This is extremely problematic with using a bow against a large group of mobs (the arrows bounce off of the hitbox and can damage passive/unwanted mobs instead).

Still in 1.8.2-pre1.

Confirmed for 1.8.7.
Fixing this would require adding a Marker
tag for all entities, which would work exactly as with armor stands. It'd be nice to see it.

May relate to MC-1080, since the fire animation appears to be linked to the hitbox
As stated by another user, this looks related to MC-1428. The hitbox also makes arrows bounce.