Of course, if Spiritual Attunement being removed from trainers, the self-damage of Seal of Blood becomes little more than a gimmick and an inconvenience. It also tended to invalidate one glyph, which was the Glyph of Seal of Blood. If Spiritual Attunement is deep in the Protection tree, then the glyph becomes aimed at tanks... who don't use the seal. When players pointed this out on the forums, Dresorull replied to test it out in a future build (I still had Spiritual Attunement as a skill on the PTR) and locked the thread.
In a related post, Ghostcrawler lays out Blizzard's intentions for Paladin mana regeneration, saying that Spiritual Attunement is critical to Protection, but they "don't actually like Holy and Ret having (it)". He explains that such a mechanic depends too much on the encounter and gave Patchwerk as one example where SA won't return mana to anyone but a tank. He notes that Blizzard would still like to tune Paladin mana regeneration -- Holy through Illumination and Retribution through Judgements of the Wise.