[_fat_santa]

Easy answer: because you are then beholden to them, same with Salesforce apps or any other "app marketplace". If they decide to change their rules or go out of business, there goes your business with theirs. Not saying SaaS apps shouldn't go in that direction, but it should not be their first play IMHO.

[dcveloper]

For niche products, I think it makes sense. For example, we had a need for a tool to generate AWS/Azure diagrams automatically. There are a ton of SaaS options in this space, some of which just leverage opensource projects to generate the diagrams. In the gov space, I can't touch it if they aren't FedRAMP'ed. I've gone through that process as a CSP, and it's near a million dollar investment. Or the vendor can just release their product as an Atlassian App and avoid that headache. Yes, you'll never be the next billion dollar SaaS vendor but could you make a 7 figures? I'm confident you could.

Rephrased, I think an agency or company that follows the AWS model of "borrowing" open source projects and converting them to a paid service would work would do well. Wrap a open source solution around an Atlassian or similar PaaS app/module.