True, most packages do not like to be 'moved' manually after they have been installed.
You can install a package into the root httpdocs folder (usually not recommended), but not currently through the Plesk control panel (there is another thread which discusses their reasoning). This can be accomplished either by manually installing the rpm, or using something like 4PSA's Integrator (their version of App Vault).
As to the open_basedir error, this is common for many packages (osCommerce, various CMS's, etc), and can be resolved by putting directives into either the .htaccess, vhost.conf, or http.include files. (this topic has been covered numerous times in other threads).
This is not a Plesk 'bug' or 'error', there is no way to have a server pre-configured for all possible scenarios. Locking down the open_basedir is actually a good security measure, then only allowing it for specific domains which have a valid reason for needing it; rather than opening it up server wide.