Dansk,
just wanted to add something that pertains to your direct question of why the WTBTS is reluctant to press certain court actions.
It seems to me that there are several reasons why the Society doesn't engage in such litigation and generally avoids unnecessary entanglements such as these, but I will give you just two big ones (aside from the obvious and major one that they WOULD NOT PREVAIL in most cases or the examples you cited)
The first is the public relations effect such a lawsuit would have. If the society brought a lawsuit for defamation it would call more attention to the supposedly defamatory information then what it would be worth it to them.
Secondly, and probably more importantly, a lawsuit would open up the doors to discovery and that might uncover all kinds of documents and records that it wouldn't like to see the light of day. Imagine a memo or report by the Governing Body members that got circulated about certains adjustments or changes for example but which was decided the other way. Such things made public would undermine the illusion.
The Society only enters the legal arena when there aren't dangers such as these and when it expects to prevail on the merits.