I'd say you should be able to quantify it. "a domain model tightly coupled to CRUD primitives" is not an intrinsic evil. If you were to genuinely save money or reduce risk by, say, moving off a relational database you would just need to pick that point and motivate for a rewrite.

The much higher risk IMO is building a hyper-flexible application from the start knowing what you need today is a CRUD app, just in case in future you need something else. That's how you get shelfware and awkward conversations.