I'm personally in full support of a showtriggers plugin (obviously if it doesn't impact server performance). I feel like it can help in cases where teleport triggers are ambiguous, for example on one map the name of which I can't remember the teleport trigger to enter the next area was inside a statue, and half the time you would just smack into the statue and not teleport because the trigger was embedded in it (something that obviously would not be a problem if you could physically see the trigger).
It could also help when a map has a trigger that must be hit by the player before a certain area opens for them to continue through the map, being able to see the trigger can help with players trying to optimize their run because they know exactly where they have to fly through before continuing.
I can see why one would be apprehensive about adding it, with people almost certainly going to abuse it and all, but if anything it's a great opportunity to iron out the long-lasting glitches in many of these maps (of course, if it's not too much of a hassle for sneaK to remove them lol.)
+1