Larian's propaganda department seems to doing a swell job convincing everyone they are poor indie devs who can't step out of their comfort zone without ruining everything. It's about saving costs and extracting money from you, the consumer. Definitely not about innovation as far as I can tell.
There is no incentive for them to try RTwP. If they do, one half of the crowd will be happy, the other half wont. They can't win. More than that, their current system has had great success, so why roll the dice on such a huge project and see if they can replicate that success with a new system? They can only lose. In addition, it will take a lot of time and money away from other elements that could have been fleshed out. It has nothing to do with their inability to be innovative. They already were innovative and it was a huge success. Now is the time to build on it, not scrap it.
Had BioWare made BG3 in 2001 or so, I'm sure you would have neither expected nor wanted them to step out of their comfort zone and use TB.