[networked]

I think a great example of a non-Basic language that succeeded because of 1-6 is Turbo Pascal. Its documentation was thorough enough that you could learn and use the language and its many libraries without external references (except, perhaps, to get you started).

Going with Basic instead of a different language for your IDE can be a good choice for another reason. It is, or at least was, good for marketing to people who write code but don't consider themselves developers. To the potential buyer of the IDE using Basic signals, "this is a friendly environment; we don't expect you to be a grizzled professional programmer". (This may not work today. The latest product from Blitz Research is called "Monkey" and REALbasic was renamed "Xojo" in 2010, both apparently for marketing reasons. The company behind Xojo described theirs at http://www.xojo.com/support/faq_xojonew.php)