To start with: as far as I know,
tag wiki excerpts are not places to share comprehensive information about subjects.
It is a short description so that when people add tags to a question, they can judge wether the tag is appropriate (e.g. that masters is about studies leading to M.Sc., not - the best and the brightest ;)).
Consequently, I find most of you edits (albeit well-intended) providing extraneous information.
Especially it is not their place to judge any topic, or provide too much of extra information and distracting from the short, concise definition (1-2 sentences long).
As a short example, IMHO the current version of united-states is better:
Topics specific to the United States.
In your edit there is a lot of repeatings (this site is about academia, so there is no need to add clauses about education and academia to each tag; on the other had, the last sentence "Use this tag..." may be beneficial):
Questions specifically about universities and academic institutes in
the United States of America and higher education at this country. Use
this tag alongside other tags to mention that your question is related
to this country.
For the longer
tag wiki - I don't know if it is that useful and worth spending time on it. In any case:
- If do verbatim copy form Wikipedia, use
> (and provide a link to a particular Wikipedia page).
- If it is only tangentially based on Wikipedia, it is so general knowledge stuff that should not attributed at all.