This is exactly my thought on the matter. It's cool that larger sites will host these scripts for you, but why should I make my site dependent on another just f

This is exactly my thought on the matter. It's cool that larger sites will host these scripts for you, but why should I make my site dependent on another just for a negligible improvement in speed / caching efficiency? My feeling is that if you're going to make your site's uptime dependent on another, at least make it for something worthwhile that you can't host yourself, either because it's too demanding or too proprietary.