> no one is typing a url by hand. We use google

I type urls by hand and do CTRL+Return to add the .com and get there.

But even if everyone is using Google, a unique name like "roollr" will certainly be easier to find than "roller" that will exist in many tlds. How will your users remember that you're the .at one, and that .com or .it have nothing to do with you?

It's so much easier for everyone to use a .com

(BTW I don't know if you chose roller as a generic example, but roller.com is apparently for sale at sedo).