Is it really that bad not being able to have it on? I understand the offline thing like reero said, but was it ever an issue that someone used showtrigger in a run to gain a significant advantage? It's mostly used to understand how to do a jump, once you learned it, you shouldn't have to turn it on again during runs..
I think it would just make some jumps easier than they should be. Call it bad map design if you want if an invisible tele trigger gets you randomly on some jump, but it's part of grinding the map to know where those are and what to look out for when running, without having to just press a button to show it to you.
And seeing regen triggers would make regen limited jumps maybe easier? Idk I feel like seeing where the regen is would be kind of cheap, it would take out the learning proccess of a jump if you can just look up or w/e and see that you're about to hit regen. For example kilo last, the regen trigger is just a box on the tele destination, but seeing it makes the cheat of jumping into it so you get an extra rocket way easier. Or aggregate, knowing where the regen is in the middle of the jump is one thing and is part of what you have to learn when grinding the map, but just seeing it while you run is something else.
That being said, I understand the point reero made about being able to see clipbrushes so why wouldn't you be able to see triggers as well; clipbrushes gives an advantage on some jumps, like showtriggers would on other jumps. I wouldn't mind if it ends up being a thing, but do we really want to just make a few jumps easier just because clipbrushes is allowed?