I dunno, if you can make a 200% attack in one round on haste, why not a 200% attack in two rounds when not? It's still "I take double normal effort to super set up an attack that results in a single deadly shot"?
Shrug. . .it's one of many examples of attempting to apply "common sense" to magic. . .
Like, speed and haste don't offer the capability to +50% or double your OB to a single attack. . .but shouldn't faster allow for a better attack?
Wait a sec, what about faster? In the base rules Haste lets you act another 100% after everyone goes 100%. . .you act longer than everyone else, not faster. (The "actions take 1/2 activity", rather than you get 200% activity rule idea is the way around that)
This falls into the logic of the spell logic. . .since as you said "How could someone at normal speed even HOPE to block attacks that are coming in twice as fast?"
Well, because this isn't a 100th level spell here, so it's effects are limited. . . .if you rationally and logically worked out the results of moving twice as fast allowing super attacks at super speed. (How about casually walking through a crowd of people moving at relative half speed, stabbing each in the neck with a dagger as you slip between their weapons in what from the outside looks like a matrix like hyper-dance of death?)
The margins on victory and a dirt nap in fencing are measured in tenths, hundreths and thousanths of seconds. . .double speed if you wanted to be rationally rational about it, would mean you could just stop rolling and everyone within reach takes an E crit to the neck. (I guess you could roll to check for a fumble to see if you bannana peel on the attempt).
Shrug, I find that normal fights rarely come down to people full attacking and full parrying as long as OB/DB splits are declared before initiative is resolved. . .and in the more common OB/DB splits two attacks are actually better, since two trips to the crit table double the chances of killing the target. . .roll that 220 OB attack, roll a 04 on the E crit, and it's a waste. . .heck, if you wanted to be super safe and dangerous. . . Hasted people can get nasty and 100% parry for 100% action, then 100% attack for 100% action, making it rather hard to get a poke back on them while they whale on you.
Regardless, you'd need to start worrying about someone coming back at you with that too. . .if that was the house rule, you'd find yourself in trouble facing it too.
There are likely 1,000 threads on this board that eventually have "Common sense would say that spell X would do Y. . .". . .which makes spell X far higher than Z level in potency. . .if you house rule it to do more, then it should be higher level than Z. . . . .
It's not like Haste isn't quite possibly the #1 or #2 errata source in all of Rolemaster, implying the scale of problems the spell has created, the amount of times it's been addressed, revised, officially ruled upon, tweaked, modified with a word or phrase added here or removed there. . . .