Hi!
​Running Parsoid as a public service (with some soft-ish API limits) would allow us to support the oft-cited user who has a dumb PHP-only box and no means to install a node service, so that has my support; however, I worry that WMF might not be the best organisation to provide this if people wanted it at large for commercial use.
I think the prospect of having publicly-accessible services like Parsoid useable by smaller wiki installer is very cool and exciting. Thought it does not solve all cases - i.e. for inter-company wiki (which I personally used extensively as a medium for capturing internal docs, discussions, plans, etc.) there may be legal and confidentiality reasons that do not allow using services crossing the firewall.