You will want the details if you know “more than average” and you’ll want some of the basics if you are just beginning to look into that certain subject.
A possible compromise would come as a two part entry per subject with Beginner info and Expert info. Or a mix of both. It seems that EOL will have something similar where expert information only shows up when it is required.
What I do believe is that there MUST be detail and complexity if the subject is complex in nature.
Say you have a page about DNA transfection, I believe that details are needed and that anything basic about this should show up merely for illustration purposes. No need to go writing stuff like “Well, you open up some space for the DNA to get inside and do it’s magic”. It’s basically right, but utterly wrong! ;)
So, although you can find great information elsewhere, Wikipedia can still be a great tool to kick-start your search or research. Just don’t rely on it completely.