[zxcdw]

Why do you suppose they left it out? Is it merely a matter of "cheap implementation" being purely subjective, and hence they might have thought it as cheap, while you seem to disagree? Or could there be a more pressing reason, but "Oh well, its cheap enough anyway" is more of an excuse?

[pizlonator]

I don't think they knew that modern languages rely on overflow checks so heavily and that the perf of overflow checks dominates perf overall.