First, I don't see Pixie Dusters complaining that Wind in the Willows/Mr. Toads Wild Ride or 20K Leagues isn't getting a clip in the their nighttime show. These sorts of complaints seem specific to Universal.
And, to be frank, I don't think Dragons, Pets, or Trolls SHOULD be in the show. While I understand the why, I don't agree with it. It's a maddening inconsistency and tips Uni's cards when adding them WITH their attractions would have been a forward-thinking move. And it's cute you're intentionally misconstruing my point by arguing BttF and Dragons are similarly out-dated. *Slow clap* Dragon's has a new film coming out next year. When is the next BttF?
That's right! There isn't one. It's an old franchise. Full stop. And while nostalgia sells merch, it's not something that drives attendance. Attendance is what matters in theme parks, because 99.999% aren't going to the parks to by a "Hill Valley High c/o 1985" t-shirt they can order online at T-Fury. Hell, the biggest complaint about the rumored Bourne attraction is that the series is no longer relevant.
And in regards to the street characters, the interaction is more important than the characters to guests. A lot guests probably think the show features Betty Boop and Doc Brown is a half-baked Rick Sanchez. They could literally put anything out there (see Hollywood Players at Disney) and the effect would be the same. More importantly, like merch, those don't drive attendance.