From the given examples, the exits aren't impossible to get to, just unlikely. Running does wonders, but so do envirosuits. Dying in DoomRL due to lack of equipment isn't exactly uncommon, in fact, it's common to all roguelikes. Isn't a medikit just equipment that's useless until you need it? Same with most things really. On the AoLT example, it's pretty legitimate to die in that way, not having niche equipment (or hardly any "normal" equipment either) is the nature of the challenge.
I'd love if envirosuits got a buff, but 25% fire/acid is actually quite nice. Better than nothing anyway. I'd actually rather that they didn't green-screen you for their duration. I know it was in the original Doom (was it?), and it's very iconic of them, but I'd try and use them all the time if it wasn't a hassle in text-mode to use them. A 25% carryable fire/acid resistance buff + I can walk across rivers and barrel pops with no downside than an inventory slot used? Most people would think that's pretty good if it wasn't for the green-screening effect.
As an aside and for another way of crossing acid/lava rivers, you could always rocket-jump across. You just have to wonder if you'd take more damage crossing by foot than the jump will do to you. It depends if there's enemies firing at you on which is better, depending on your build/items. So we have rocket-jumps (common but painful), phases (common but random), homing phases (uncommon), envirosuits (rare), lava elements (unique), and invulnerability globes (situational). That's not including boots, medikits, tele-staffs, running, zerk skulls, zerk packs, rockets for wall clearing and all the other ways you can make it easier on yourself to get across the damn rivers. You might occaisionally get caught out, but there's plenty of ways not to take too much damage.