The point regarding IMEIs was that if carriers get antagonistic enough, it would be possible to change the blacklist that (some) carriers use for stolen phones into a whitelist that disallows any third party phones.
Outside the US, governments take the promise of being able to take a SIM and put it into an unlocked phone very seriously, so I'd say this is a strictly local problem. In fact, I'd wonder how Deutsche Telekom's regulators would react if T-Mobile (DT's US subsidiary, at least for now) started doing something like this (that they probably wouldn't permit in Germany).