You have to compromise the ruleset further to accomodate RTwP playability. Just look at Kingmaker.
They'd be dealing with two combat systems to design and balance, which isn't exactly easy and raises questions like should rule parity between the two be a thing. If they were to opt for rule parity, then the Turn-Based option would come out crippled inevitably by the concessions that have to be made in favour of RTwP.
You have examples of games that attempted both modes and were complete clown fests, like Arcanum and the Might & Magic series.

Last edited by Iuris Tantum; 16/06/19 10:34 PM.