I recently had a look at the wereraven statistics from Curse of Strahd, and the way it looks to me is that this would be a really good offer for kenku.  

These are the changes I can see that a kenku would get, following the rules from the Monster manual on lycanthropy. 

1. First of all, they gain immunity to non-magical or non-silvered
weapons, which is always useful.
2. Their passive perception increases to 16, which also doesn't seem to
have any negative effects.
3. Their beak can actually do damage, making them more deadly.
4. They gain the ability to transform at will in to both an
inconspicuous raven, and a much more terrifying hybrid-raven, which
sounds pretty good.
5. Finally, they gain the ability to fly anatomically. For a kenku,
this last one is a really good one, as both the Monster Manual and
VGTM both state that this is something kenku crave desperately.

With the above considered: **if a Wereraven was to offer a Group of kenku lycanthropy, is there any reason I've missed that would mean they'd have doubts about accepting this offer?**