Elemental cast times are long and there are much fewer options for Black Mages to bring this down. Divine Benison caps na spell cast reduction by default at level 90. Cure spell cast time can be reduced by 35% through Cure Clogs and merits, 12% by Orison Pantaloons +12%, then with Incantor Stone, Loquacious Earring, Orison's Locket and Royal Redingote you get 19% cast time reduction (34% if your /RDM) from Fast Cast. If you're SCH subjob, you get 10% from Light Arts. In either of these cases, you're cure cast time reduction will also be capped.
WHM gets Solace, SCH does not. You can also cap cure potency without any body piece and use Orison Bliault +2, but a more realistic number I would say is around cure potency +44% (thus Orison Bliault still wins.)
Other jobs don't even have Cure V either. So yeah, WHM is still aeons ahead of other healing jobs.