you know, i get that the melta-gun was fucked up, and wasnt at all accurate, and i whined a lot about that, but to be honest...i feel like either there is a weapon that functions like that--a super shot gun, or they should make/add one...
Here's the thing. You want the more lore-accurate weapon damage and portrayal? Play on easy mode. That's how it's supposed to feel. As for the melta gun, you might want to check out the 40k RPGs as there are WAY more varieties of plasma/melta/flamers/bolters than the single one you see on the TT. As in thousands of different patterns and models for each. I'm more than happy to see differences in weaponry if it can be clearly explained to fit in setting. The fact that Space Marine took place on a forge world that had all sorts of experimental weapons is perfect for me.
The problem is that a basic Space Marine is desigNed to be the equivalent of the elite of other races(this goes for basic Chaos Marines as well). The performance of a space marine v. the basic troop types of other races should, design-wise, be an unequal affair, requiring greater numbers,or the intervention of that races elite warriors to offset this. So, the bolter should be an elite weapon, dispensing with basic troops rather easily 1v1. That being said, basic Orks and Eldar should need an equalizer going toe to toe with Space Marines or Chaos Marines. That equalizer shouldn't be gimping out the bolter. It's less of an issue with Marine v. Marine, and those two factions will undoubtedly be the most heavily populated.
I feel you highly underestimate the F2P culture. I have no doubt the orks will outnumber all other factions.
It basically did that. If you hit an ork in the head twice they died. You could cut swaths through the ork boy mobs that they threw at you provided your aim was good enough.