with how small the numbers are i think it makes a difference to show it. even you listed what could arguably be a broad range of numbers!
there's a big difference if you're like, fighting 3 fly guys and each of then do 1 damage, than if they all did their max. you could block 3, or 9! that's a massive difference in how you're gonna approach the situation. 9 is just short of half the starting hp, and 3 damage feels like "eh, i'll heal it next round." y'feel me?
and yeah. the purple fly guy sucks. i hate that guy >:(