Is it a good idea to load the css files from page.tpl file instead of .info file
It is bad idea, on so many levels I'm sure I can't list all.


Conditionally included stylesheets will get cached by various proxies and served with no respect for original conditions.
Modules like CDN will not be able to work on your CSS files to speed things up.
Aggregation and cache modules will stop working as well.
Search engine bots will get confused and may think you are trying to trick them by serving different version of a page to bot, and other one to bot disguised for an user - risk of google ban.
If, in future, someone will redefine page.tpl.php for certain content types, you will have the same file described in many places - easy way for inconsistency and styling bugs.
CSS provided by modules might end up in other position to your own than they are now, this can cause hard to diagnose display bugs.