I main a rogue, and I'd give my left nut to have our GCD increased to 1.5 sec. I think it's the perfect amount of time to react to on-the-fly decisions and it feels very smooth.
When I saw that all DK specs/presences had changed to a 1 sec GCD in MoP, it completely killed the pace of the class and turned it into a frantic whack-a-mole style gameplay. I don't know wtf Blizzard was thinking with that change, to be honest.
You should have kept reading. The GCD wouldn't stick at 1.5s, it would scale with haste. That way a DK in tier 19 would play the same as a DK in tier 17, just faster.
The DK 1s GCD change was a huge positive for our class, because as DKs geared up in previous expansions, they were always forced to switch to Unholy presence. That's the primary reason why they changed it.
I don't mind hitting buttons on a 1s cadence; I actually enjoy that, but obviously YMMV. Personally, I just don't want to be forced to hit a button every single single 1s "slot" or lose significant performance every time I have to move, or lose an instant of time on target, or use a utility ability, or scratch my nose. That's what GCD-locking is all about.