Handing out merits is sometimes hard. I know when my merits build up and I havent handed out source merits in a while I get a lot more generous and know that if I dont hand out all my source it gets burned, much better to be in circulation than have them vanish.
I agree with you. But it seems to me better to spend time and give away 50 merit for a good post than to encourage poor quality / junk posts.
That's highly subjective and I personally think there's no right or wrong way to spend your merits. (as long as you're not abusing the system)
What you think is a junk post, might be quality for someone else.
I know some people only consider posts with +10 sentences merit-worthy, while others only look at the content and general helpfulness of the post.
It's good that there's a lot of diversity between merit sources, that's going to "cover the most ground" IMO.