The reason for the move to LGPL is simply to make it easier when consulting. Normally when accepting a fee for programming, the work is owned entirely by the client. I have worked for a number of companies which required that the work produced was co-owned by both them and the client, but this was always a contentious issue.
The LGPL license sidesteps this nicely. Work done extending AgileWiki plugins remains part of AgileWiki. Custom plugins developed for a client are owned entirely by the client.