This is mostly false. Each hit is not considered a different Attack unless it comes from a different source. So even if you roll 5 12's, but don't hit Structure, it's only one Critical hit roll. It's stated under the 4th bold entry "Natural 12", after the "Heat, Flak and Special Weapon Attacks" entry.
However, it does improve the odds of a Critical Hit, I do grant that consideration.
Well, I’ll be damned. It does say that.
Easy fix. Don’t use that sub-rule. We don’t. We like it that way, too.
Before the switch we we barely ever getting critical hits. Typically, a mech was fine, then stripped of armor from a successful attack, then dead.
Having a lower damage per turn, but more damage more often makes the game feel like a return to form as a game of attrition. You’re firing ALL of your mech’s guns, not just one big, single gun. Because it trickles out damage over time the internal structure gets hit more often on different turns. Each turn is an opportunity to get a critical hit. All it takes is 1 damage.
It’s also better for kids who hate it when they fail an attack roll. Playing rules-as-written they shoot their guns, and one bad dice roll later they’re upset because they missed with their one, and only, shot at the enemy. I like giving my kid more chances to shoot, then shoot again, and again. It “feels” more fun this way, and less frustrating.
And critical hits started becoming more common.