I don't think that being cliched makes makes it necessarily bad in its own right though. For example, if it was the first anime that you had ever watched, would the ending still seem cliched and unoriginal? If so then fair enough it is a bad ending, however, if not then maybe the reason you didn't like it is because you have watched so many different animes that it would take something as original as Death Note to pique your interest? P.S. Since my tone is not made apparent from text based input I would like to clarify that I am not being confrontational in any way I am just curious as to why ppl didn't like FMAB's ending