Because then it's an English Pale Ale.
Call a thing what it is. If it quacks like a duck, walks like a duck and looks like a duck, only an ass would call it a turtle. I mean, I don't want to piss off anyone, but isn't it obvious?
If you want a classic American Pale Ale, choose one or a melange of the Four Cs and use American malts and yeast. If you want a classic English Pale Ale, use a classic English hops like Fuggles or East Kent Goldings, as well as English malts and yeast.
If you mix them up, you've still got a yummy beer - it's just taking a liberty, stylistically, and the AHA and BJCP style sheets will tell you that. Call it "WW's Pale Ale" and leave it at that.
I absolutely love the idea you're proposing. The Shipyard Fuggles IPA is a damn tasty beer! Plus, if you start exploring single-malt, single-hop beers (SMaSH), you'll be experiencing one of the most fun and educative things you can do as a brewer. Maris Otter and Fuggles...yum!
Cheers,
Bob