Ok. Rant incoming...
This might sound mean, but it's not intended as such. (It's also not a HP fanboy post; I can see why it's successful but I usually find myself bemused by it all...)
I don't really know why you're surprised that Harry Potter - a literal billion-dollar franchise with a huge worldwide following, ten (and counting) theatrical movie releases, several tourist attractions and a whole heap of naff merchandise - is getting picked for a 20-year anniversary over Bionicle - a franchise which has a famously niche subculture within the already niche subculture of AFOLs.
I also don't get why you're mad about Bionicle getting a little easter egg shoutout. You're mad because Lego isn't paying respects to the franchise, and to illustrate your point, you're giving us an example of Lego paying respects to the franchise...?
If you're mad that Lego has seemingly forgotten about Bionicle, then guess what; they haven't. They gave it a shoutout in The Lego Movie, Takanuva almost made into TLM2, concept art and the whole Toa Mata team are on display in the Lego House, Bionicle easter eggs are still showing up in other sets - heck, while it wasn't what most of us G1 fans wanted, they even gave us a whole new reboot with new sets, worldbuilding, artwork, animations, games and a Netflix movie.
Even today's Lego sets have Bionicle roots. Would we have so many different posable figure sets with towball-socket joints if Bionicle hadn't existed? I doubt it. Would Ninjago be the blockbuster theme that it is today without Lego learning the ropes with Bionicle? Probably not.
Even the people involved in Bionicle haven't forgotten. TTV is running canon contests with Greg. We've had people like Bob Thompson, Christian Faber, Stuart Sayger, Pop Mhan etc. coming out of the woodwork to do interviews. I mean, Faber's even trying to get his weird vision for a potential whole new G3 off the ground.
But Lego are a toy company. They exist to sell toys. They don't exist to pay tribute to every single one of their dozens of past themes.
G1 ended over ten years ago. G1's popularity was waning long before that. And G2 didn't meet sales expectations; in fact, it met them so badly that the last line of sets wasn't even universally released everywhere. (Yet Lego still felt it was necessary to wrap up G2's story instead of leaving it on a cliffhanger...)
Unfortunately, that makes it unlikely that we'll see another Bionicle set; even as a small tribute set. Not impossible, but not likely either. (I'd love a bonko GWP; but again, when you consider the whole consumer audience of GWPs, how many of them are actually interested in Bionicle?)
But even if Lego had completely forgotten about Bionicle - again, they haven't - do we actually need a new set from them?
The community is still building and posting their own creations online; not to mention fanart and other fan projects. Builders are still uploading bonko projects to Lego Ideas. We've had at least two attempts at a large scale 3D exploration game starring the Toa Mata, with the latest one currently in production and getting Lego's official blessing to continue development - how often does that happen with fan games that borrow existing IPs?
The fan community tracked down and released the cancelled Quest of the Toa; the white whale of Bionicle fans for more than a decade. BZP and TTV are still up and running. Communities are still interacting on Facebook, Twitter, Discord etc. There's multiple wikis devoted to archiving the entire lore of the franchise. There's an entire site devoted to archiving the entire media franchise: games, artwork, animations, set instructions, even internal style guides that we were never meant to see.
I find Faber's 'the legend is in your hands now' stuff a bit trite, but I guess it's mostly true. Bionicle is the thing we grew up with, it's the thing we still love, and no amount of disinterest (or perceived disinterest) from Lego can change that.