yes you do want to touch the server templates.
they are the very basis of your servers. like will you run in mod_php or mod_fcgid. that is a huge difference. Do you have slavenameservers, send an email with customised text etc. those go in the templates.
the plans you need for quotas on webspace, bandwidth, sub-servers, databases available features etc.
The plans have been extracted from the templates because there where many requests so hosters can upgrade/downgrade customers to other plans more easily (automated way)
The old way was to switch a client to another template but all the quotas had to be done manually. Now you can switch to another template (from mod_php to mod_fcgid) without changing quota’s and features.
Also now you can switch to another plan without the server being switched to a different execution mode.
It became much more flexible, but the initial set up needs to be done properly according to what you will sell.