It is so bothersome to reinstall everything. Is it so difficult to provide the chance to simply upgrade from 6.1 to 7 without erasing the disk? As elementary OS is based on Ubuntu, there must be a way...
The release upgrade guide suggests this is not possible currently, so you cannot do an in-place upgrade from 6 to 7, for this release upgrade:
a fresh install is currently the only officially-supported way to upgrade