Sonic and Halo leap to mind. Sonic is stuck in an unplayable mess of the old school crapfest (as in, the bad parts of retro) and can never seem to catch up with the times. I'll admit the only reason I want Halo to die as people might stop trying to rip it off and make something innovative for the FPS genre again. Say, make a Time Shift game but make it playable. Tomb Raider suffers from the same problems as Sonic as well.
I will happily defend any series however that can be reimagined, and this included Final Fantasy and Megaman. While both series have an embarassing number of titles that date back several gens they don't have an established continuity and its possible to reimagine the cast and/or world as needed. This is more passable with Final Fantasy than with Megaman since FF is evolving with the times, seeing as XII didn't have awkward transitions into battle screens which really have been hurting most JRPGs lately. Unfortuneately the series is starting to feel like its repeating itself as the apparent premise of XIII is very similar to VII. Megaman meanwhile creates a bunch of sequels to a single series with about five seconds of plot (save Megaman VII which I contend had one of the best endings in the series) and almost no real progress made. However, the series seem to eventually stop as new ones are made.