I'll always enjoy Easter eggs ... I'm actually disappointed that I haven't found more of them in WordPress. Still, I know if I ever set up a blog for my parents (for example) I'd want to disable any that they might accidentally find.

Certain demographics will never really understand an Easter egg. Whether it scares them (because it looks like a hack) or distracts them (i.e. the Facebook Contra code) I know just the presence of an Easter egg would be upsetting. Easter eggs that animate and display a self-destruct countdown are entertaining to those of us in the know, but they utterly fail the "would my parents understand this" test.

I also don't see the feature as unprofessional, but it can definitely be confusing to new/infrequent WordPress users.