The important thing about sapper is that it exists...
Sapper is the first trap that you can fire from R&D/HQ that can trash a program (and this is where it shines tbh, it is a really crappy piece of ice - i shall retract this statement i was bitter about mimic at the time) , and as easy as it is to play around (by having a killer) you still have to play around it which is what makes this card important.
Having played sapper a reasonable amount recently, this card really shines in decks that aim to rush. It adds an extra layer of psuedo gearcheck. Against rush decks, most players will focus on finding their fracter early. Sapper means that central pressure without a killer installed becomes risky buisness. The combination of these two things means that sapper has the effect of slowing down runners that play around it whilst losing the corp no tempo and doubling up as a decent enough piece of ICE.