Sounds like something that might be better fixed with either a PSA or more of an RP house rule. I'm not sure that having a large pile of points in a heavy hitter and then having that hitter get a bad streak of luck is really a problem with the rules because I haven't seen it happen often enough to be a frequent game-decider. This is especially true if you are using larger forces like company-on-company or larger as one mech, even a big one, just can't be that big a percentage of your total firepower.
However, if your problem is that mechs with big damage numbers missing causes too much of a swing in your games, maybe use some of the existing PSA's that allow for re-rolls or add your own PSA to help mitigate this. Maybe something like one of the following:
- If the MoF is 2 or less, the mech can deal half damage, rounded down on a failed attack.
- The mech may reduce it's damage by the target's TMM in order to ignore the target's TMM on the attack roll.
- On a failed attack, the attacker may instead deal up to X damage where X is no more than one half of normal damage rounded down. The mech may deal no more than [pick a number] total damage this way per engagement.
I would prefer something like those for a couple reasons: First, as PSA's, you can find a way to apply them only to the Mechs that are likely to give you problems without affecting mechs that are currently OK. Second, it avoids adding a large number of extra dice rolls. Third, I think your rule might actually end up making the heavy hitters LESS frightening to the enemy because with four or five dice rolls, there is a decent chance you are going to miss at least one even if you only need a 5. So, now there are a larger number of mechs that can risk standing in front of that beast and still expect to survive the turn. If you have a mech that does 4 damage and you only need a 5 to hit, the odds are 50/50 that you will fail one of those rolls. With 5 damage, the odds are 60/40 you will fail at least one roll. So, you will not only flatten out the low-end of damage, but the high-end as well. Since Alpha Strike moves fast and things dies quickly, I'm not sure how that will affect the game. It will probably make games last a turn or two longer, but I'm not sure how that might affect the relative power of different mechs. Finally, PSA's are already a thing in Alpha Strike, so you wouldn't really be adding any new layers, just using an existing one to suit your needs.