...as per issue title.
Views 7.x counts ~400k installations while D7 itself ~600k which makes it an estimated 65% of Drupal 7 sites out there using Views. I think this deserves core attention.
From my point of view I think this should all be part of core. Otherwise people are stuck for an endless time at the previous version like we have seen in CCK. CKEditor in oposite is easy to uninstall like noted in #1927424: WYSIWYG: CKEditor upgrade path and namespace collision with contrib? as it does not really have important data except some settings, but views upgrade would be a real show stopper. We have also uninstalled update_status module in past, but this was free of harm like ckeditor may be. I have no idea what has been changed in the view data structure, but doing data structure changes without providing an upgrade path sounds always wrong to me and is one of the key troubles I've seen with nearly every major Drupal upgrade in past. Such Drupal upgrades should never released from my point of view.
I hear you. Almost all my setups that were upgraded from D6 to D7 in the past were a pain because in the end I had to "manually" migrate everything. And I mean *everything* as in start from scratch :/
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