Buying digitally i think you should know what you are getting into. No physical disc, relying on a company to make the game downloadable for a very long time, no ability to sell. However if you wait long enough you will get a very reasonable price on a steam sale... and at that point its so cheap, who cares if you can't sell it back?
Last year there was a court case in Europe involving Cisco going after a website that was selling used licenses of their software. Europe's highest court ruled that Cisco cannot block the sale or trade of used licenses, but any seller must render the software unusable upon resale (http://www.computerworld.com/s/article/9228762/EU_court_rules_resale_of_used_software_licenses_is_legal_even_online)
Don't know where they stand on how easy developers have to make the transferring of licenses. Still, a little bit of extrapolation and you can see why Microsoft has the 24h check thing. They allow you to sell licenses and just implemented their own way of making sure the software's unusable upon resale.
As a developer of software, I'm a little biased here, but I think if software wants to restrict its usage to one person, it should be able to, just as consumers are able to not buy it.