The problem is when they maintain two product lines that overlap. Nvidia should have done this from the start, rather than releasing the 9800 GTX+ AFTER the GTX 280 had already come out. They started a new product line while they were upgrading the old line. There never should have been a 9-series in the first place. They only created it to look like they had new offerings to compete with the ATI 4000 series.
Nvidia hasn't been able to create a legit low-end 2xx series cards. In fact, the entire GTX 2xx line-up is only a single chip. The 260, 280, 285, and 295 are all the same chip. The only difference is clock-speed, included memory, and newer cards went through a die-shrink. Nvidia never bothered to create a new budget or economy line from this chipset. Therefore, their only option to stay competitive is to rebrand old technology, they have no new technology to market.
Nvidia just sat on their thumbs for too long when ATI wasn't able to compete, and now that ATI has better options, they're caught playing catch-up.