I have no idea why devs think pioneers should have an extra sight range than the other engineers in the game, but this is dumb. Ost already has the best HMG, the best none doctrine mortar and LMG, and strong line infantry. I don't see why they should have another strong advantage layered over this already strong faction.
It's already difficult enough to counter MG spam in the early game, the sight bonus makes it even more difficult to pull off successful flanks or can give spotting for their mortars while safe inside their own MG's firing arc when trying to counter with indirect fire. They should have the same sight as the other normal engineer units.
Both soviet combat engineers and pioneers have extra view range. And that was given so that they can be used in the field tactically i.e. spotting. If you can't counter mg spam then your a Newb thats just a fact.