1. It is ambiguous. Ambiguity is bad.

   The word "Net" has numerous meanings already. Worse yet, "Net" is an abbreviation for "internet". This leads to the misunderstanding that ".Net" applications must have something to do with the internet. This in turn makes it harder to convince people to upgrade their pre-.Net applications.

2. It's already taken, by a Top Level Domain, no less!

   Friends of mine have been in a number of rock bands over the years. Whenever they think of a new name they first check on Google to see if the name is already taken. Microsoft's marketers, on the other hand, are so stupid that they not only failed to check if ".Net" was taken, but they chose a name that was obviously taken.

3. You can't google it!

   When you search for ".net", google treat it as simply "net". Hence, searching at Google for anything related to .net is a heck of a lot harder than it would be if they'd chosen a better name.

What's a better name, then?

Oh, don't ask me. I just like to complain a lot :-)