I do read a number of blogs, and I have to agree that's there's a lot of redundancy. But I stick with it for a number of reasons:
1. Although there is often more information on FT, I simply don't have to time to read it all. FT is full of gold, but you have to go panning for it. For the return on time invested, the blogs hand me the info on a platter.
2. FT threads can sometimes get very difficult to follow. Even though I've been participating here for a number of years, I still don't know all the lingo. It sometimes seems as if FT posters are talking in some secret code. Information on the blogs is already digested.
3. Using a reader (I use Google Reader) allows me to go through all of the blogs that I follow pretty quickly. When I spot a redundant post, it only takes me a second to mark it as read. Without a reader, visiting the separate websites for all the points/miles blogs that I follow would be way too time consuming.