i do honestly think things could get balanced in a way that would mean they wouldn't have to restrict it. having limitations on what you could choose would hardly even be better than just having defined kits, so i think they'd need to go all-in if they did it. if they nerfed burst bomb a ton (like i said i think making it >50% ink consumption would be a good change) and buffed some of the weaker subs then you would definitely be able to see unique strategies come up. there are plenty of weapons that would like a point sensor, for example, to the point that i could definitely see people opting for it if given the option, at least casually
though, a thought i just had while typing that: i wonder if all the problems would be solved if you could choose TWO sub weapons for your kit, rather than just one. after all, the left bumper goes completely unused in regular splatoon gameplay. that way you could dedicate one of your subs to a lethal bomb, and the other to a utility sub like point sensor or sprinkler