Our main tool (app.thorntale.com) is this concept! But yeah, the problem we've noticed is that without a lot of constraints, the generated presentations look very disjointed and tend to be incoherent.

My theory is that while Claude and similar can generate html-based documents fine, presentation slides are such an unconstrained medium that it's closer to image generation than code generation, so getting it to have a stable style is much more difficult. We constrained our app to a Notion-like architecture for this reason.