I wouldn't call Batman Beyond unloved. Considering the impetus for the series was to have Batman in high school, the end result was better than it should have been.
Now, if Bruce Timm and company wanted a challenge, they could have wrapped up something like The New Adventures of Batman, or shoved Road Rovers into JLU canon.
When this episode was aired, it looked to be the final episode of what they'd started with B:TAS, and took through Superman, Batman Beyond, Justice League, and JLU. It was intended to book-end the show that started it all.
Watch the last scene of "Epilogue" again, and compare to the opening scenes of the first B:TAS episode they produced:
http://www.youtube.com/watch?v=-8V7ylqttcY
So "Epilogue" isn't about "Batman Beyond" so much as Batman, a statement on why Batman is such a compelling figure.
I remember buying these for my son and him watching them in a marathon session while I was cleaning the basement. I'm not completely sure, but this episode was an episode or two after a "current" episode that suggested a Batman/Wonder Woman romance was brewing, so this was kind of a letdown from that heady notion.
But that doesn't mean this was a bad episode, of course. I thought it was interesting to bring Batman Beyond back.
Batman Beyond was well loved. There was serious talk of a live action movie, and the series had been renewed for another season before the production staff was moved to create Justice League.
This comment is unrelated to the video, I'm just wondering if anyone else is getting the banner ad at the top that is promoting Vinegar as a way to eliminate Chem Trails?
Now relevant: This is my favorite episode of either this or Batman Beyond.