I agree with Andy. Especially the bits about enjoying when I do play and yet not playing enough.
Also DB is an "element" game, closer in spirit to DBA than to WAB. Not that there's anything wrong with that - but it is a different experience I think. It also has quite a tight timescale (finishing with the arrival of the Vikings) and covers the properly Dark Age bits of the early medieaval period (as we're now supposed to call it) which narrows the appeal.
I think its a colourful and interesting period, and quite like the fact that the lack of much concrete knowledge gives a little freedom to the interpretation of armies and fighting styles but there is a bit of an impression that the period is just "men in brown with sticks hitting other men in brown with sticks".
With WAB you could play with any armies from bronze age to renaissance. And even (if so inclined) play "time tunnel" games of Hittites versus HYW French both of which factors opened it up to more people.
I still think there's a market out there for a WAB replacement. I'm a little surprised neither CoE or WaC made the leap to fully occupy that space. I think if anything they were almost too soon after the "death" of WAB - I know I didn't pick either up because I was quite content with WAB and in particular James (and Steve's) El Cid and AoA.
Hail Caesar has a good following (and gives a great game) but again is "element" based and aims for a different gaming experience.
However WAB still works just fine too, maybe it's time for another El Cid or AoA day later this year..?