> For 95% of applications you can just distribute a single SWF file
You can do the same with HTML5+CSS+JavaScript, all in a single file. You can even include images, audio and video e.g. with data urls.
data urls encode things in base64 format so bloat up the file. Also the user agent can't just seek over them, requiring it to parse the entire included base64 content. There are better ways, but sadly nothing cross platform: