Bomat Courier is one of those cards that gets played
because of the detrimental trigger (and the other stuff that goes with it, obv). This discussion also came up with
Nyx Weaver, among others.
Wizards Magic R&D team often provides guidance for our Policy team, on how they want games to flow, how mechanics should impact game play, etc. It's actually a wonderful collaboration! And, R&D was quite clear: losing resources like this is detrimental.
Also, as Francesco hinted at - policy says to look at the trigger in a vacuum, not in game context (except for universal triggers where detrimental/not depends on whose turn it is - e.g., Howling Mine).
“Hey, I'm losing a resource!” –> detrimental (in a vacuum).
“But I want to have that happen!” –> context suggests benefit, and here we are…
d:^D