I'd echo this - I know a decent amount of DBAs/data devs who need to generate an ERD once a year for some giant overview thing for their new VP or whatever, and Visio just doesnt cut it, graphiz has a million ways to slice it, etc.

Maybe that market isn't that interesting to you, but the value prop for 100 bucks a month (since most real schemas that have the problem of requiring visualization are going to be >50 tables) for one schema that I then get to go cancel or w/e isnt that strong - It'd be enough that I'd consider writing that graphiz layer I keep screwing around with.