The download sizes of these files are like these:
- Yahoo UI - 232 KB (fullsource), 20KB (minified,gzipped)
- EXTJS - 547 KB (fullsource), 147KB (minified, gzipped)
- Prototype + Scriptaculous - 169KB (fullsource), 29KB (minified, gzipped)
There are still no established ways for minification, many websites do not use them. So users end up downloading large files.
Are we not wasting too much of bandwidth, power, apart from creating pollution due to CFC emission - in downloading the same files for each website.