No. Just no.
I played a few ranked games during the end of this season, mostly just to see if I managed to do better than bronze
(where I ended up years earlier when I still played ranked - this year I placed Silver 5 and finished Silver 2-almost-promo-to-silver-1)
and later to help my friend get Plat
(I played 45 games in total, including placements only lost 9 in total, one being a placement),
and sometimes I played TT and ARAM, but most of my time spent playing, I was playing NORMAL DRAFT. I've got a combined amount of games in ND of almost 3500+ games in my years in this game, and maybe 2000 in any other game-mode (ranked included). If not for Normal Draft, I wouldnt even have picked this game up. And I'm serious; I would NEVER have started up games, knowing that each and every one of them would affect my ratings, unless I played blindly into the enemy team.
There's no way you can get away with saying that it's "unhealthy", because the reason people actually played ND, was so that they didnt have to play blindly into the enemy team and not being forced to play ranked. You've effectively stripped away any and all reason I had to play this game, and with me, alot of other people.
To us, what you've done is "unhealthy". I dont know the exact numbers in percentages - and I'd sure like to know - but even if it's as low as 2-3%, for those players, ND was the reason we could play the game.
Not everyone wants to play ranked and have the stress of their ratings hanging over their heads. Not everyone wants to play blindly into an enemy team at the same time you fight with your own team to get a certain role - or NOT BEING FORCED INTO A CERTAIN ROLE. This was what ND provided - a way to plan out what champ you could play, and wasnt able to play, due to the enemy team, and a way to get out from under the always present champion of your hate, meanwhile not forcing you to play new champions with the threath of losing ranks, or that promo you sought to win for your fifth time (just to lose, because some dude wanted to learn Sion jungle after never having played him before - and instead of training that champ, they just picked it in YOUR promo).
I'm fairly certain that the percentage of people playing ND isnt actually that low. I honestly believe that you just want to force people into your new queue, the Ranked Flex one, by taking away one of their other choices that would almost certainly impact your new queue negatively. By disabling ND, you take 85-90% of the ND-players and forces them into RF, while the rest either drops the game or play TT/ARAM/BP - which kind of boosts your numbers in RF.
I'm quite certain, that if you didnt disable ND, most people would not even touch RF after Solo/Duo Ranked had come, they'd stick to ND or play S/D Ranked.
This decision has GOT to be the dumbest decision ever, it's even dumber than when you brought on Dynamic Queue, it's even dumber than the junglechanges you've made, and it's dumber than the role-updates you've done (ADC-changes, mage-changes, and now assassin-changes).
I know alot of people dont like change, especially drastic ones, and that change in itself is causing uproar.
But you're literally telling people to either endure blind picks, where every cancerous champion is going to be present due to no bans, where you can never play in thought-out teamcomps, or risking their rankings because they want to expand their champion-pool. That's got to be the dumbest shit ever thought out by any gaming company - NOT counting those companies that tanked.
Like, really. Drop this idiocy.