The main issue with Nextcloud Talk that I see is that it's part of the Nextcloud-as-a-monolith model that they push, for understandable reasons. However, a lot of organizations have serious needs around chat with deeper integrations. For example, Rocket.Chat can enable one-click video conferencing, on top of all the other myriad of features, right there where users already are communicating with each other and with services, bots, and notifications by using either BBB or Jitsi, which is great, and means we don't need to have users switch tools just for video calling. Talk lacks this kind of integration in general, which just makes it tough, and it's (imo) not quite mature and suited as the alternatives described.
Similarly, between BBB and Jitsi, there are lots of options to do more advanced things than just integrate them with another chat client, like embedding those conferences into web pages via Jitsi's API for that or BBB's Wordpress plugin / API or into an LMS like Moodle (also on the wishlist) via plugins (for BBB or Jitsi). Jitsi also has the ability to live stream in addition to record meetings (BBB can also do recording). Basically, if I'm going to spend valuable server resources (and transitively money) to run a video conferencing solution, I want more mileage/"bang for my buck" than Nextcloud meet offers.
I think Talk is a great starting point for anyone with casual interest, limited needs, or just exploring video conferencing as a tool, but once we get to the proverbial big leagues with heavier-duty use cases, it's hugely beneficial to have one of these more fully featured tools. That's also striking at one of the huge advantages of the Cloudron platform - everyone can deploy the right-sized solution for their needs with ease and spend the energy on evaluating and transitioning tools as it's necessary, rather than getting mired in the administrative overhead of operating an existing one.
As a parting thought, I'll add that today I find myself leaning more toward Jitsi than BBB after (finally) a positive experience with an event leveraging the public meet.jit.si and thinking about the live streaming capabilities...frankly, as I've sworn up and down repeatedly in this thread, either would be great. If the hardware demands are too extreme on BBB, then let's go Jitsi. The control and privacy are really the banner features, imo, and both do an excellent job on those core requirements.