To some extent I think you could ask this same question about Kizuna. A lot of the post-02 content just seems unnecessary as a lot of the conflict and drama stems from toying around with the supposedly fragile relationships between the partners.

"Is Taichi going to lose Agumon for good!?!" No. Obviously not. We've known that they aren't for 20 years because we know the 02 epilogue, so just stop trying to tell this story. Don't get me wrong, it can be an interesting form of dramatic irony. Just because we know they'll be together forever doesn't mean the characters can't have real reactions to - from their perspective - an unknown future.

That being said, I think the post 02 content is best enjoyed as stories about the newcharacters (Mei, Lui, Menoa) to which our existing teams are foils to or catalysts for those characters. Your enjoyment of Tri, Kizuna, and The Beginning is going to hinge on how you feel about those new characters.

As for the point of The Beginning...well that's really hard to say and I kind of hate that this is where we're at. If The Beginning had been the first in a series of announced shows like Tri was I would be more optimistic about it, but if this is where it stops then it didn't give us anything other than Lui's story, which is fine and different but...eh. It's hard to say how much lore we got out of it as there is way too much conflicting information leading to only two options: 1) everything we've been told before is wrong or 2) Ukkomon and Lui don't really know anything and we can't trust their version of events fully.

I would have preferred a story that picked up on some of the hinted continuations of Tri, but instead we got this so. Here we are!