Why using exe compressors?

[[Psych]]

Light protection from reversing by newbs (although it's not just vanilla PECompact on my trainers; some additional bits to it in there), smaller file sizes if not by all that much (still good ratios on my releases so might as well), PECompact doesn't flag up anymore than the original file (due in part to the dev working with major AV companies). That's basically it. Look at it the other way, there are basically no negative effects are there.