If you feel that you have a problem with insufficient merit awarding, then perhaps you could increase your standards for the awarding of merits.
I haven't looked at OP's merit-giving history, but your suggestion is generally a good one. Merit sources probably shouldn't be handing out merits willy-nilly and should have fairly high standards. Then again, Theymos did want sources to give merits to posts that are just "good", especially if they're made by newbies. That was in a PM he sent last September if I'm not mistaken.
May I add something to your idea? IMHO, "Fairly high standards" should be in accordance with ranks. A high ranked member should be more challenged to receive merit. It's not really newbie-biased, though. It's just more difficult for them to produce a quality post than old, high ranked members, who are experienced ones. Besides, merit can be a catalyst to encourage new members to be active and contributive rather than just be here and wear a signature.