snip
Every time Random spread was introduced into a halo game, it was met with widespread condemnation from the playerbase. EVERYTIME. It was patched out of Halo 2. People still complain about it in Halo 3. It was eventually patched out of Reach. The lack of spread on precision weapons is something H5 was initially praised for.
Also, paid developers came up with Halo 4, a massive collection of bad ideas that were heavily tested prior to release- so let's not use their salary to prove they thought this through carefully.
They CAN tweak things like RRR, magnetism and aim assist. The test playlist does this on a number of weapons. Adjusting these values is PROVEN way to influence a weapons effective range without making gunplay feel unsatisfactory. Not just proven by Halo, but also by many other shooters with an interest in differentiating weapons by range.
If they measure success by gameplay datapoints, rather than by what makes the game feel enjoyable and rewarding to those playing it, then they are doomed.
Data helps, but entertainment is an art, not a science. The goal shouldnt be "reduce the effective range". It should be "reduce the effective range in a way that feels satisfying". The trick is the 'satisfying' part, and Random spread won't do it.