This is a fundamental and very true point - as long as the web remains as inanely centralized as it is presently there will never be stability/usability on par with desktop applications. Not because web-apps are worse than desktop-apps but because users can never manage to build up their skill sets before the web-apps are changed and "improved": in conclusion this situation is the bane of sanity and the course of the rise of the Slow Web movement!

That's an interesting point, I had not thought of that. I always think of this from the point of view of the webmaster, ease of change after launch seems like a plus to me. But the way you put it I can see that there is a significant downside to this as well (and I'm very well prepared by Moniker to see that downside sharply).