For my two cents on this, I personally don't mind the mostly lack of new characters so far, after all this series is meant to focus on the returning bladers and all that.
Yeah it lacks the variety and new faces are always nice to see. However, my issue with the Burst anime as a whole is that they almost never ever acknowledge their past bladers that aren't the very major characters. This isn't like Bakuten Shoot Beyblade with G-Revolution, or Metal Fight Beyblade with Baku, 4D and Zero G where they actually show us most of the past season bladers actually existed. It may not have been all of them but it's still better than how Burst handles it.
I'm also just going to be talking about the anime, I cannot speak much for the Manga as I have barely read it.
For smaller role characters though... When's the last time we've seen Joe after his own season debut? Okay he's a recent example... but what about Norman? Do we see him again, even as a cameo after his season? Nope. Kyle? Nope. Hearts? Nope, and he had a big role. Ghasem? Nope. Blind? Nope. Boa? Nope. Pot? Nope... Hope. Joshua? Nope. Laban? Nope. Ruwei? Nope. Houi? Nope. You get my point. Burst rarely ever has the characters shown, even in a cameo after their seasons, and no flashbacks or being imagined does not count. Yeah there's Kurtz, and the first season cast had a cameo in God, but that's it.
Compare this to MFB, even after Baku we were shown most of the world champion teams. We saw Wang Hu Xhong, Excaliburs, Wild Fang, most of Starbreaker, The Garcia's (for better or worse...), even Lovushka got a cameo! And the first season cast were shown in Baku, some even appearing in 4D. Yeah, not everyone returned, but it was still a good amount of non major characters who returned.
And also the original BSB trilogy. Even after the first season, during G-Revolution, we were still shown White Tigers, BBP All Stars, The Majestics, even the Dark Bladers, Zeo and the Saint Shields got a cameo in the special ending. Again, not absolutely everyone returned, but it was still a lot.
Burst's new characters that don't serve a big role are flavour of the week at best, and they almost never make a cameo again, which makes the world of Burst feel so much smaller than it is, we need more, even small cameos at least.
My Cho-Z Reaper Deathscyther .12.Cr concept render, click below to see!
No I don't plan on doing more yet.
I should probably go back to making fan custom Zero G beyblade concepts again