To be fair, I don't believe that was done to stop people from rooting their phones. One of the most common ways for phones to become damaged/bricked is for OTA

To be fair, I don't believe that was done to stop people from rooting their phones. One of the most common ways for phones to become damaged/bricked is for OTA updates to fail; the HTC Vision/G2/Desire Z method means that if that happens, the phone still works. Which is obviously better for the average user. That said, it's not much of a stretch to believe it was a nefarious attempt to block rooters from rooting either.