@Anonymous Because they wanted to make a sniper rifle. You can't just add a sniper rifle as alternative fire mode to an AR - that would be way too universal (or the stats would just have to be bad (and hence 1 or the other mode would be practically unusable anyway)).
Havoc alt fire is NOT a sniper rifle. It's damage dropoff starts very early, so it's intended use range is <200m - not a sniper.
And it's never used even in it's intended range, because the stats on it are just terribly bad (I guess they wanted to be overly conservative testing the new mechanic).