Interesting ideas… it would seem possible for Discourse to be available preconfigured with certain plugins and theme elements to suit some particular use cases like a news site.
Re. point 3, the self-managed instant install: based on my own experience, the gumption and ability to work through the installation and setup process feels like a minimal prerequisite to self-management. If Discourse hosted unsupported 1-click installs, I imagine sites running out of storage, log files accumulating, upgrades failing, etc. – and unhappy users who weren’t prepared for the responsibilities facing a crashed site vs., I don’t know, an ala carte support menu? I see some staffing challenges and PR pitfalls with that scenario.
I appreciate the open-source nature of Discourse and enjoy self-hosting a small forum, but if I were an organization with a lot at stake and little in-house talent, the cost of fully managed hosting might seem a small price to pay.