I didn't jump on it at the time, although with hindsight the writing was clearly on the wall for shadow word: pain. This weekend, a blue post confirmed the change and explained why:
We removed shadow word: pain from scaling with haste because we thought shadow dps was too high with all three dots hasted.That last sentence is completely baffling because unless I have just developed sudden onset aphasia that's exactly why they did it. So we'll just ignore that bit. There's some other stuff about best-in-slot gear and theorycrafting, I stopped reading. The message to take home is that Blizz thought shadow was doing a little too well on the test realm and they've come up with an easy way to rein it back in.
There is a bug where you can get big sw:p dots and keep them rolling at that magnitude forever since the spell gets constantly refreshed. It's a nasty bug to fix. However, that isn't why we removed sw:p from shadowform.
I'm completely ok with that. If I'd wanted to be top-dog dps I'd be playing my lock right now, or my hunter, so I understand when Blizzard takes action to maintain class balance. But, as usual, I'm a bit disappointed about the way they've gone about it.
Shadow word: pain is already the weakest of all our dots. It has been riddled with bugs from the start of the expansion, outpaced in damage by devouring plague, and practically dwarfed by vampiric touch. Without haste scaling, that weakness is only going to be amplified. This for what was, in Burning Crusade, a class-defining spell and one of the most lethal dots in the game.
I know this isn't game breaking: if Blizzard gets their numbers right, whether one spell ticks for two hundred or two thousand is irrelevant at the end of the day. I'm just very sad to see such an iconic spell decline so miserably over the course of only a few months.
The designers have taken a very pragmatic approach — they needed to tone damage down and they found an easy way to do it. But it's not good game design to go around making two essentially identical spells work in different ways for convenience's sake — or to use flaws in the game that they have ignored since the expansion launched as the excuse for doing so.
Ok, so the bugs are too tough to fix: remove the refresh mechanic then, or nerf it to one of those 'extends duration by up to xx seconds' deals. Or nerf vampiric touch's spell co-efficient, which was basically doubled as a quick-fix buff to start with. There are a hundred ways you could balance shadow's dps without guaranteeing that one of the class's core spells fails to scale with gear and falls more and more into disrepair.
We'll all continue to cast shadow word: pain because it is basically free damage — and maybe that's the real point of the spell's current fortunes. But I'd gladly put up with a few more complications to see it restored to its former position of fear and respect and see it finally scaling properly with gear.