Why does the Equalizer pistol/SMG have such a feeble range compared to all the other Remnant weapons

Short range is intended, read the back of the card in-game. Balance-wise it used to make sense as it was one of the stronger weapons, but it's kind of fallen off since everything else got buffs.

Except of course for the Destroyers cannons.

And the Observers lasers.

And the Nullifiers Space Balls.

And.....

Same reason why there are guns (in both ME3MP and MEAMP) with a weird ass mini-delay after pulling the trigger. Or why there was a shotgun that could only fire one shot before requiring a reload.

It's BioWare's idea of game balance. Apparently guns that perform well in one aspect - as the Equalizer did before everything else caught up - must have some weakness to make up for it.

Other games simply vary their available weapons in giving them different roles in different situations without going to this extreme.

How about the Inferno these days? I have the feeling it's in need of a buff too, especially when the Shadow seems to be superior.

Yeah Infernior definitely needs a buff. In fact most URs are still underperforming.

It is basically a shotgun alternative for vanguards. It's OK in single player because it's easy and fights are much shorter, but in multiplayer the range limitation is highly annoying.

Agreed with all but the bold. That part's just silly.

If you want a moderate-damage, quick-priming weapon, the PAW is peerless among the ARs. If you want to actually kill shit quickly with your gun, very much not so. Soned, Revenant, Cyclone, and Thokin all outdamage the PAW. Valkyrie is excellent if you can consistently land headshots. The PAW's principal advantage against the field aside from priming was accuracy, but that's been largely erased with the new AR scopeless accuracy mod.

Further factoring in that upwards of 95% of the playerbase have the PAW at much lower level than most of the other options above makes the comparison even less favorable in practical terms. It's certainly good, but best by a wide margin? No.