Q: Can't I simplify this by merely reducing the amount of media used and by telling them that too much tv is bad?

A: Sure, but that has problems with it, the first being the phrase 'too much' and it's subjectiveness. The second is the implied false dichotomy of 'bad' and 'good'. Children will grow to be adults that will eventually hear the benefits of 'good' media consumption, typically pointing to the educational merit of its content. Form is a crucial part of the discussion and most proponents of educational uses for media consider only the content, never aware that the form plays a big factor in affecting meaning. In addition, connotation and denotation as part of semiotics is a cross-disciplinarian tool useful for visual literacy, reading and writing, textual criticism, or simply developing strong human communication skills. 
In addition, telling them to cut down on their media use is, from the kids' point of view, parental control and just more 'parental empowerment', while giving them the tools to evaluate media themselves is 'child empowerment'.
Q: Doesn't it seem hypocritical of you [and of me if I were to follow what you suggest] to critique technology so harshly when you used it in your messages, for this website, and for work purposes?
A: That is a double-barrel question that was partially answered in the 2nd and 3rd message I gave. The question can be broken down into at least these two components: 1) The seemingly hypocritical function [which I will explain to be a false dichotomy later]; and 2) the definition of 'technology'