Definitely agree with Dragon Quest 7. It's got cool mechanics, and I love job systems, but man, some parts of the game are just needlessly tedious and it drags for no reason at all. It's based around finding different tablets and completing tasks in said tablets, but some of those just feel so disjointed and pointless to the main plot of the game. The game could use a good trimming of fat, and it makes the idea of additional playthroughs such a turnoff.
Another game that immediately comes to mind is Mario and Luigi Dream Team. The game could have gone on for like, 15-20ish hours, and we'd have another fun game in the Mario and Luigi series, but it goes on for about twice that length and leaves a sour taste in my mouth. What could have been a fun game, turned itself rather bland.