It's not that hard, let's do math
4 ez8: 720x4=2880 hitpoints
3 panthers: 800x3=2400 hitpoints
Howie doesn't cost more because of 6 men, it costs more because is on top of arty food chain, it outrage EVERYTHING and has the best aoe/building killing potential on top of non standard barrages for utility.
Now, I know teamgamers and memers would like ez8 to get jackson pen, sherman he, panther durability and be better than anything at everything..butit already fullfill with high pen at for anything but king tiger and ai against anything.
There's no tactical thinking, you always want one more of it, and you can simply spam it as the most cost efficient all around killing machine.
"A bit better" than panzer 4 is laughable.
You keep forgetting that the great armor value of the Panther will inflate its potential HP when deflecting shots, armor and hp are tied together as durability.
It is a bit batter than a Panzer 4 at a higher price (plus being tied to a commander), still dont see your problem.
E8 has 35 more armor and 80 more HP than an OST P4, 50 more pen after the P4 buff.
All you are doing is getting upset by words like "a bit" and "slightly", which doesnt lead anywhere. Those tanks are fine as they are (P4 buff was deserved, thats why i want a slight 76mm sherman buff because its in the shadow now.)