I've tried doing the same thing. But having a non-linear increase in the number of hits causes weird results when things like Artemis and AMS gets involved.
Also, regarding the '2' table; UACs really need the higher number of hits... Thought that's easily fixed by just giving them a +1 on the cluster roll.
The only inversions are on the 3 and 4 rows and the 4 row could be 1,1,1,2,2,3,3,3,4,4. I didn't do that because it would put all the change at the low end instead of distributing it, but if that change is made Artemis can only reduce damage on the 3 row, which is only used by the MML-3, which it would be very silly to use with Artemis.
AMS rules are just plain screwy and it's not worth leaving things broken just to avoid having to change them. Right now AMS stop more missiles when there are more missiles coming in in a short amount of time (ie. from a single volley from a single launcher) rather than being overwhelmed. It would make more sense if AMS rolled for some value on the cluster table and stopped that number of missiles for the round with a preference for longer ranged (more tracking time) or higher damage (larger target) missiles first depending on how good you want mixed volleys to be.
Ultras are their own mess of problems. I don't think they'd be worth using with the 2 row nerfed, but I don't think they're worth using as it is now so that didn't really enter into my thinking. I think perhaps they shouldn't use the cluster table at all but do something with margin of success. The cluster table is a reasonable approximation of fragmentation explosions (LBX) and with range based modifiers of shotguns (HAG) and missiles with dodgy seekers can work however the rules say they do, but in my FPS experience landing multiple hits with burst fire weapons is much more based on skill than luck.