Autocannons are fine. The AC/20 and Gauss are the only two that give you high alpha pinpoint hits, and the AC/20 at least has severe range, velocity, weight and size issues. You can't use an AC/20 with an XL engine unless it is in a vulnerable arm location, which restricts the speed of mechs that carry it. The AC/20 is also much less efficient than, say, an equivalent weight in SRMs. All of the other autocannons require you to expose yourself and face the enemy directly in order to get full damage, due to their lower damage and high rate of fire. This is such a disadvantage that 'dakka' builds are basically useless in competitive/high level play. Also, the idea that ghost heat doesn't affect AC's is a little off base - I don't know if you remember when dual AC/20 builds could fire simultaneously, multiple times in a row, but it was intense.
Gauss, on the other hand, is an issue, but only because you are seeing mechs that can carry more than one of them, and fire them both together to hit a single pixel on an enemy mech. Change the Gauss charging mechanic to only charge one at a time, and problem solved.
Edited by Postumus, 30 October 2014 - 07:32 PM.