If you actually do the calculations, you will realize these are the best gloves available, behind tier 4. Let's compare these to the ever-popular Prismatic Mittens of Mending (23 int, 26 stam, 55+heal, 5mp5)

If you put a +18 gem and a +9heal/2mp5 gem into the gloves of saintly blessing, and take into account the spiritual guidance talent, and improved divine spirit buff (which every raid should have) you get
33
+18
+ 9
+ 7 (socket bonus)
+ 7 (spirit healing bonus)
74 total +healing

So let's do a final comparison
By upgrading to the epics from the blue mittens, you gain:

+19 healing
+22 spirit
+ 1 stamina,

and lose:

3 intellect
3 mp5

So, they are actually quite powerful gloves, if you look at it right.