The other advantage of the JB approach is it's one click install and upgrade. No schema migrations, complicated issues with DBA hoarding permissions etc.
little did you know, the source code for atlassian server products is already available for any paying customers. It's not FOSS, but if you need to run this yourself, and customize it, it's already possible. But of course, you will be responsible for keeping it updated (patching vulnerabilities from libraries etc).
[1] https://www.atlassian.com/legal/software-license-agreement
A lot of what makes Jira so broken is that it is way too flexible, and this flexibility has costs in terms of performance and stability. There’s a damn good reason why I used Chrome back in the XUL days for FF; because XUL FF was not performant or stable for me back then.
https://chat.goodbyeserver.org/
It's an difficult position Atlassian are inflicting on tens of thousands of customers. Atlassian's self-hosted products are uniquely flexible, being built on a plugin architecture, and many orgs have indeed customized Jira extensively with plugins, notably ScriptRunner [1]. Atlassian's Cloud plugins have their APIs, but have nothing like the same flexibility. A lot of functionality just isn't possible in the Cloud architecture. It's a bit like Firefox moving from XUL to an extension API.
In my opinion, the most customer-respecting way forward would be for Atlassian to open-source their discontinued Server product line. Go to the "open core" model with the clustered Data Center product as the upsell. This avoids screwing over their customers, and if their Cloud product really is as good as they say, customers will migrate to it naturally over time. It's the kind of damn-the-torpedoes move I think Mike CB would like.
But over the next 3 years, lots of painful migrating or evaluating-of-alternatives will need to happen, and perhaps a non-Atlassian forum for sharing experiences will help.
[1] https://marketplace.atlassian.com/apps/6820/scriptrunner-for...