It's true that comics fans often get excited about things that wouldn't excite non-comics fans.
And the reverse is also true, which is why they picked Donner.
DC needs to attract people who don't normally read comics, so they're dropping names the "man on the street" might know. With all due respect to Dick Donner's possible story-telling skills (we'll see, won't we?), in the end this all boils down to stunt casting, and no more.
What's interesting is that DC and Marvel can pull writers from any old place and the fan reaction varies from "cool!" to "let's wait and see." Whereas you can bet your sweet bippy if they said Dick Donner would be DRAWING Superman, everyone would scream, "But he's not an artist!!!!"
Here we see another way the Marvelization of DC, and the industry as a whole, has shaped things. Comic books are now about the art, period. Stick whomever you like in there to write the things, just give us pretty pictures to look at.