The Chrono series.
Chrono Cross was somewhat okay, but the plot was one giant black hole and having 40 playable characters with cardboard cut-out personalities was a letdown, especially with Chrono Trigger's closely-knit party. Radical Dreamers was a good game. I have no idea how the supposed remake was worse.
The series has been dead ever since, aside from "Chrono Brake/Break" being trademarked a decade ago. I pray the dream team will eventually get together again and make a sequel more connected to Trigger.
And the worst part? SquareEnix sent cease & decease letters to two fan-made sequels, possibly the best fan games ever: http://crimsonechoes.com/ http://www.opcoder.com/projects/chrono/ We would think they did this because they were working on an official game, but by the looks of things, they really don't give two shits.
"At E3 2009, SE Senior Vice President Shinji Hashimoto remarked "If people want a sequel, they should buy more!"."
...yeah, they really don't care.