Yeah, but let's not forget that they were an add-on to the original trilogy as was a bunch of other stuff. IMO some of it added to and some of it subtracted from this larger story. Robots and Eternity I'm ok about but I'm on the fence about the addition of Galaxia. I don't think it's as bad as some make it out.According to "Prelude To Foundation" the robots were there all along. Even Seldon's wife was a robot.
The starships in the trailers appear to encompass black holes, which is a step forward from the nuclear powered and even fossil-fuelled starships of the books.

. If his family owns the rights they're already filthy rich (and more so with the Apple series coming) so it could be the income from more books isn't worth the dilution of the brand. They're not obligated to increase shareholder value like a public corporation is. More interested in the family legacy than on pumping out quick, short term profits.