Nothing’s stopping anyone from putting the disc in when you want to play it. You don’t need DRM to pretend your PC is an old console.
I’m a bit confused on why anybody would want themselves and others to be legally forced to do so each and every time you want to play the game though.
I’m opposed to DRM. Even so, I wouldn’t ask for a refund because of the CD-checking kind of DRM. (That’s easy to get around on PC anyway, even if you’re not great with computers.)
Anyway, I suspect the people who were demanding refunds had a not-insignificant influence on the decision to go DRM-free. (Money talks. BS walks.) In other words, I owe them (however petty their actions may have seemed) my thanks. Now I don’t have to introduce any additional risk to my (potentially irreplaceable) Clannad disc each time I want to play it.
Also, some computers don’t have disc drives built-in, so an external drive would need to be used on such setups. People who believed they’d only need to use one once – at install time – had ample reason to want a refund. Digital might not work either; not everybody agrees with or wants to/can use Steam.