I guess it's not quite as easy as whacking up something in HTML and CSS, which might justify the recent trend towards supporting that in as many things possible

I guess it's not quite as easy as whacking up something in HTML and CSS, which might justify the recent trend towards supporting that in as many things possible. I also think that the attractiveness of one of these projects can vary quite heavily depending on whether you're a UI/UX designer or a programmer, and there's always the opportunity cost of giving up working on something new and fancy.