It's not a bad idea, but the tradeoff is usually you'll have to define your models twice. For whatever reason, that tends to happen anyway, so not that big a drawback in practice.
Eh, in my case I prefer writing raw SQL for the API side of things - it's more apparent what's going on in code that I actually tend to wind up debugging down the road. As a result I don't really feel like I'm writing models twice - I model then code, then just read it directly, if that makes sense.
You are ultimately still right, I think - just a personal nuance I guess.
