Now, imagine if, instead of running for three years, it ran for ten.
Now imagine if it wasn't actually a cartoon, but a story splattered across books, comics, online serials, winning BZP stories, and random answers from the author lost to time.
Now imagine if it didn't gain a massive following, but more of a niche audience, when it first aired, thus making access to most of those resources spotty.
Imagine what would happen to every new Transformers series if that were the case.
Spoiler alert-- it would flop like a bad diver from a 100 foot drop on a pool. And it would hurt about as badly.
That is the most compelling evidence that Bionicle 2015 will be a reboot-- to do otherwise would be an awful, terrible, horrible business decision.