A 70% chance to his is a 70% chance to hit. There is absolutely no reason to conceive of a 01 as being somehow "better-aimed" than a 70.
There's likewise absolutely no reason not to.
Some people - who include me, but unsurprisingly not you - think it would be preferable if Evasion was DoS/F based, because if it was, it would be more granular. And thus better able to reflect the difference between, say, a Cultist trying to punch an Arbitor in the face, and a Lictor trying to punch an Arbitor in the face.
Disregarding all modifiers, a Cult Initiate has a 25% chance of making a successful 'Punch the Arbitor' attack.
The Arbitor, meanwhile, has a 38% chance of Parrying the attack entirely.
A Lictor has a 65% chance of making a successful 'Punch the Arbitor' attack.
While the Arbitor still has a 38% chance of Parrying the attack entirely.
As far as the system is concerned, there is no difference between trying trying to Parry a very human enemy with little or no combat training, and trying to parry one of the most perfect organic close combat killing machines in the universe.
If you change Evasion Rolls into an Opposed Roll against the attacker's Attack Roll, Lictors suddenly become a lot harder to Parry than your average Cultist.