Only one of these apps is free - Crystal. And it says it's temporary right on the App Store page and why. The author is making an entirely conscious, clear-eyed business decision. Here's a bit from the email he sent to his testers:

A big thank you to all 1200 of the testers who have helped shape Crystal into a solid application. I'm sorry to everyone else who didn't get a spot to test it, but the good news is, you can try it now for free!

Why Free? I want everyone to experience Crystal for themselves so as a thank you to my early adopters, I've decided to make it free for a very limited time.

Whats the catch? No catch, but I would like to request you help me out with Rating, Sharing, a quick survey or donating a little money below, I do have a wife & 2 kids to feed

Perhaps there's a race to the bottom in mobile apps but it probably produces more useful things than the race to tut-tut the decisions or generosity of others.