I don't see any harm in those threads mentioned in the op. I may have posted once on a 'Good Morning', but they are usually on page 2 by the time I log in.
The Congratulations threads are a bit monotonous with their regularity, but still don't see a problem with them. Ignore them if you don't like them - it's not as if you don't know what the subject is going to be.
It is a public forum, for the members to post comments on whatever topic takes their fancy.
I am not aware of any subject restrictions for the forum other than child pics(obviously), and don't see any reason why there should be.
There seems to be some sort of snobbery amongst certain posters, that suggests their posts are the only interesting/good ones. This thread is a prime example.
Here's my crayons, I'm going to start drawing now and leave the 'grown ups' to it.