It's a small nerf to prevent haste abusing like it was before. You see, with haste +4 before huntress could outrun every melee enemy in the game and kill it with the spirit bow. Haste helps with food, positioning, getting distance, exploring. Like this IS a lot for a ring. That's why it got nerfed a little bit. But it's still viable
Previously, you only needed +3 to move at double speed, and you don't need that to kite monsters. I just played mage with a +2 Ring of Haste (the new version in the beta), and I was kiting monsters all the time: just walk away and eventually you'll get an extra turn of movement. Zap the enemy, they step next to you, and you repeat. I ended the game with extra food, so all the wasted turns from kiting didn't negatively impact my game. Though, honestly, I did a lot of melee, too. I wasn't kiting all the time.
Just don't walk more than one step away from a ripper or succubus or they'll leap or teleport to you.