the default in 5e isn't half. the default is a HD roll. You can choose to take half if you want to.
the mechanic right now isn't good in that you reduce the benefit of higher HD, it also dramatically increases the importance of con - which would be okay with rolled stats or more points, but right now it's kind of the worst of all worlds.
IMO, you should have the option to roll or take average on each levelup, that's inline with pnp and opens up build options a little more (especially as Larian seem to promote save scumming anyway, so you can always reload a few times till you get max or close to max).
It also impacts things a lot because enemies don't do their average damage. They roll, which actually makes everything potentially more deadly.
a level 10 wizard normally can have 60+10x con bonus hp. (they could also have 15+10x con bonus too). The rolled vs flat averages does in theory work out the same over a bunch of levels anyway I guess.
I know at most tables I've played at, GMs have tended to allow rerolling 1 for hp too, so I've probably been spoiled
by that house rule lol.
Thing is as well, in a CRPG you're likely to fight a lot more than you do in pnp...
anyway yeah, I'd advocate roll or take half, make it player choice, it's not like it would be a difficult mechanic to add considering random number generation is basics with just about any programming language.
