I think the spec play barely adequately on live with tons of Haste. You still get gaps where there's nothing to push and you're just sitting there, and there's nothing you can do to remove those if the RNG feels like sticking it to you. Increasing the CD of Blade will make this worse, and likely force players to choose between talents that help fill the gaps (badly) and whichever ones bring the most DPS. Either way, that feels bad.
From late LK through to MoP and even WoD Ret had a full or very nearly full rotation, and in Legion it got filled up the the later tier bonuses. Then in BfA they decide Ret has to feel like a poorly geared Arms Warrior and spend time just sitting there. Meanwhile Fury gets to run round with a completely full rotation where they get to show the difference between good and bad by choosing the right button to press. It's not often these days that there's much question of which button to press as Ret, other than sometimes wondering is one should use Wake of Ashes when you have 1-2 Holy Power because you want that finisher Right Now. Oh, and we lose that choice in SL too - Wake will only give 3HP, so we can't over-cap unless we had enough HP to use a finisher anyway.