Your objections are misguided. I can't say they are outright wrong, but...
A (good) CDN speeds up content by having distribution points close to the client. An added benefit of a shared CDN (like this) is that resources can be shared by multiple pages, which will mean the cache will be shared by multiple pages. DNS lookup can be a factor in page load time, but parallelizable HTTP requests (especially to a location that is close by) can usually make up for it.
Google's recommendation is to use between 1 and 5 hosts per page: http://code.google.com/speed/page-speed/docs/rtt.html#Minimi.... For the type of clients this CDN is aimed at (people who don't have their own CDN) it is unlikely they have more than one or two hosts already used, so this CDN is likely to be useful for them.
HTTPS support is required for domains served over HTTPS. If you aren't using HTTPS then don't use it.
A (good) CDN speeds up content by having distribution points close to the client. An added benefit of a shared CDN (like this) is that resources can be shared by multiple pages, which will mean the cache will be shared by multiple pages. DNS lookup can be a factor in page load time, but parallelizable HTTP requests (especially to a location that is close by) can usually make up for it.
Google's recommendation is to use between 1 and 5 hosts per page: http://code.google.com/speed/page-speed/docs/rtt.html#Minimi.... For the type of clients this CDN is aimed at (people who don't have their own CDN) it is unlikely they have more than one or two hosts already used, so this CDN is likely to be useful for them.
HTTPS support is required for domains served over HTTPS. If you aren't using HTTPS then don't use it.