Some of the DLC you're saying is just nickle and diming tends to offer as much content as a single player campaign in your average triple A game. Most of the DLC for Civ V is worth owning.
The map packs are most definitely a cash grab, and I'm not interested in the scenario included with each civ dl because I've got enough content with just the base game to last me forever. If I could pay $5-8 dollars for the two expacs (67%-50% off the $15 bundle price) I'd do it in an instant. Instead, I'd have to pay $15, which essentially corners me into the complete edition.
If one is new to Civ V, however, the complete edition is most definitely worth the price.