100% Lisa Su is a control freak and thought Zhou was a threat. Cult of personality CEOs do not generally end well for the company
And the software ecosystem was already in place (even though everything had to be rewritten).
Had Apple gone with Be instead, most likely all three companies would have gone bankrupt before 2000, and Pixar would be Jobs last successful company instead.
Where NeXT went wrong is in being astronomically expensive, which drove its addressable market to nothing. This is the exact same mistake Jobs made with the Lisa. The significantly inferior Apple II platform was far more successful.