I agree, there is a lot more that tech blogs could do to help the reader. The problem is, that kind of extra detail isn't really possible without specializing -- and if you specialize, you limit the size of your audience.
The other problem is writing the stories: it would be awesome to have a writer for every kind of topic, so that every story can be tackled with complete background knowledge... but that's just not feasible. Instead, most tech blogs have writers with 'beats' that they cover -- but even then, if the 'green technologies' writer is out for the day, someone else has to tackle it.
So for the most part, we tech bloggers just try to get a good grasp of the technology, and then boil it down into a form that's easy to read and understand. The resultant story quality is variable and depends a lot on how much time and effort you put into it, and your background knowledge -- but I like to think I do a fairly good job :)