I radarshoot with shotguns constantly in my games. The only real downside is hitting barrels and destroying items, and it's not enough of one to stop.
I mean, this is the entirety of hell's arena. Radar shoot around until you find a cacodemon or baron, drag it to a corner, and cornershoot it to death. Really, I do the same thing for the whole game up until the enemies start becoming easy/run low on shells/etc. Build doesn't matter, actually, I do this on every build. Melee, Pistol, Shotgun, Chaingun. It seems to be the optimal strategy to me. I guess I don't really consider corner shooting or radar shooting to be what makes DoomRL unique. What I thought made it unique when I first started playing was the music, the sound effects, the weapons (almost all ranged), the class and trait system, mods/assembles, special levels, saved data between games (schematics, medals), etc. There's a whole lot that is unique about this game.
I would rather than corner shooting have something more intuitive (as opposed to having a tutorial to explain it) or explicit. I think corner shooting is less interesting because almost all the time it's a no-brainer to do it. Just the math on how long it takes to get to a corner, how likely you are to get hit in getting to the corner, and how long it will take you to kill the enemy leads to me heading for the corner. I don't know what exactly might be nice to have instead. I agree that you can't just remove it, because there needs to be some form of strategy in the game. Maybe if enemies with ranged attacks that could blow up walls would attack the corner. Or maybe just something to even out fighting without a corner a bit. Reloading while moving? Another thought that interests me on LOS is non-radial LOS. it was an FPS, maybe you could only see in a cone.