Hold it... i wonder if "REM_ming" (or strictly deleting the
guilty sections) some of these xml content would do just that.
Mind you, i haven't tried it yet or even if i will (from curiosity) as it could possibly crash the game, but i think the basic idea of giving the power to select which Mega-Events could be made active right at the configuration steps (Tick Abundant-Asteroids, etc) by selecting any from a drop-drown list as a new optional feature (In version 2.0... i hope!) would simply do IT for us all.
Think about it - you've got THE Jagged Knife only to expect - you dunno when, but it's sure to happen ONCE and will not occur along with many others unless you explicitely define it as a pre-game option.