I was there on that fateful day, were you?
Fan-made sequels generally don't hold much interest to me.
An analogy: I wouldn't care much for a fan-made follow up album to, say, a Metallica or Tool album.
When it comes to a series like Castlevania, Metroid or Final Fantasy, sure, part of what I like are the series mainstays. But recreating those is not enough to make an entry in that series good. What makes the difference between the good and bad entries are the people behind it. Much as I'm interested in anything Metallica or Tool do, I'm interested in the games made by the people behind the games I like.