Yes, that was intentional. This just changes the way Ruby and Chef are installed. The most common use case is to deploy VMs that don't have the appropriate Ruby version and the Chef gem installed. Installing Ruby and Rubygems is different in each OS, and available versions may differ too. This motivated the properties to customize how all this was installed.
The Omnibus packages install an entire Ruby distribution with Chef already there in an isolated directory, so there is no need to deal with gem version conflicts and with different OS packages/versions; the Omnibus installer does that dirty job. Users will end up with a self contained Chef and Ruby that does not modify the system Ruby, if any. Installing Chef with Omnibus is more clean, simple, removes some failure points, and takes care of the OS specific stuff for us, so I decided to make it the default option. It is also the way Opscode recommends to install Chef. Users with an already existing Ruby can also use the "advanced" way to install the Chef gems here, if they prefer. --- Reply to this email directly or view it on GitHub: https://github.com/jclouds/jclouds-chef/pull/26#issuecomment-27167733
