I don't have a problem with the original vendor. If the vast majority of users don't have a problem with a relationship like this, and think it's acceptable, then I don't see a strong argument for making it illegal.

As for making the product unusable, they can do that anyway through OTA updates, which are applied at the user's discretion. If you think that's a problem then you should regulate that, not some other technical issues that may or may not be related.