This was entirely meant to make it so DKs were not unfairly punished on Alysrazor.
That's it. Don't read anymore into it.
The Death Strike hotfix was intended as a buff to single target Blood DK damage. Normally it’s not a big deal if one tank class does slightly higher or lower damage than other tank classes (as long as threat isn’t a problem), but when you have mechanics that greatly inflate tank damage, then it can be a bigger problem.
We discussed buffing Heart Strike or other attacks, but one of the concerns we commonly hear from Blood DKs is they feel torn about spending runes on Death Strike versus other abilities, and we didn't want to change their rotation in the middle of a patch, just modestly buff their damage.