Divine Sacrifice is party only. NO one cares about DSac.
Divine Guardian however is 20% raidwide damage reduction. This is what people want. Any sane tank shouldn't even have to ask if they should get 2/2 DG. ESPECIALLY now that you can do it without having to bubble AND it can now be done every 2 mins instead of 5.
The same tanks that don't see any worth in DG are the same idiot tanks that refuse to Sacred Shield themselves.