This has been discussed at length elsewhere in this thread, on elm related discussion boards, and in multiple articles.
Ports is the -preferred- way to interface with javascript, certainly, and when its inherent limitations aren't a deal breaker, its being preferred is entirely sensible.
It is not, however, an escape hatch in any meaningful way, hence why people were extremely upset when the actual escape hatch was disabled by maintainer fiat.
Other than performance I do not see any limitation of the async port system. You can call back from the js side. It is an especial way, I agree, but one that keeps the Elm paradigm intact. It is quite clever. It is "different", but I do not consider that a limitation, but a matter of preference.
Not every tool, has to solve all problems.
But I do think people should spend more time articulating what their tools don't do, rather than what they do :)
I don't particularly mind if a project holds their opinions sufficiently strongly that they mark the escape match big red letters with "BY USING THIS YOU ARE VOIDING YOUR WARRANTY, IF IT BREAKS YOU GET TO KEEP BOTH HALVES" and then tapping the sign any time somebody asks for support with using it, but it should still -exist-.