But that cannot help with interactive pages or web applications, and in other cases it can be a bandwidth/latency tradeoff.
High latency is always bad and should be avoided. Serving content from the served contentinent is the minimum requirement for good UX.
I exaggerate a bit to prove a point but the gist is definitely happening, we're just waking up to it slowly.
With stuff like web sockets/Web rtc /whatever new awesome sauce is out today a lot of that has changed, but that's still really the same spirit of ajax anyway, just with actual persistent connections instead of hacking it with long polling.
You can write a shitty system regardless of paradigms used.
You can write a beautiful system even with painful primitives.
All it comes down to is how much time and talent you're willing to invest, which is admittedly a cliche and non answer, but true nonetheless.
Static HTML only has a potential latency benefit on first load due to the ability to save render-blocking resource roundtrips. For later requests where those resources are already fetched, it only adds bandwidth overhead.
