I don't think Dominion has jumped the shark. Empires seem one of the best designed expansions ever. I might be wrong though. Some cards seem complex, but I still feel Adventures was just as complex if not more complex. But, hey, I'm biased as is most people on these forums.
As far as there not being enough Debt cards, we get 12 cards total including Events/Landmarks that make use of Debt. Guilds only gave us 4 cards that gave coin tokens, so I'm not really complaining. I would like to see more split piles though. And, who knows, since Split Piles don't require extra components, we may just end up getting more.