<Snipped quote by Earnest Evans>
Fair enough.
Seriously though, she only has some of his abilities, not all of them. As far as the series has gotten, she can't generate a reality marble, or make multiple copies of NP's in midair (IIRC). And she's not as good at it as Archer himself is. And if she burns through all her prana, she'll cease to exist. So it isn't that bad.
Come on, we know those aren't major setbacks. Reality Marbles are nice, but being able to summon Noble Phantasms beats that the fuck out. Not being able to make multiple copies of a Noble Phantasm certainly wouldn't stop you from creating a single instance of the most powerful one and roflstomping anyone who isn't another Fate character or similarly powerful. Being limited by prana hasn't set back any of the other Fate characters I've seen in other multiverse RPs, since nobody ever bothers to keep track of it.
Archer! Ilya is an immensely overpowered character, and is almost guaranteed to end in colossal power-wanking between the three or so characters who can keep up. At least Superman is largely restricted to what he can look at or touch.
Beyond that, Ilya can get prana from other people. It's not even very difficult, just smooch a comrade or grapple someone.