The rework was leaked and there was a rushed response by Riot, and I feel it was more important to launch the rework successfully rather than acknowledge the rework was a new champion. Subsequent reworks were less extreme, with Trundle and Sejuani following a month after Karma, through to Tristana's rework. The only champion to get close to a rework to the extreme of Karma was Lee Sin, which stopped on PBE after the community & pro-player backlash.
Morello pretty much said 'old Karma' was not coming back during all the discussion, which was the final reply on the topic. Karma getting LCS play in mid/support roles pretty much finished it, especially after Berg's Karma pentakill.