This was intended as a comment, not an answer. But I was too lazy to divide this into separate comments - since it is too long - and I also think that in this way it is more readable.
Feel free to edit this, if there are some inaccuracies.
I wanted to check for myself whether there are many bumped old question. (For the sake of simplicity, let us say that old means older than 7 days.)
I went through 150 recently active questions (as of this moment; timestamp shows 2012-09-26 18:26, of course I've spent some time typing and formatting this text).
I found out - to my surprise - that 8 old questions were bumped because of a new answers:
140384
192049
191538
7695
124130
186506
199767
198435
(The names of the links are numbers of questions, but I've put here links directly to answers, that caused the bump.)
Some of them were edited after being bumped by a new answer - but I would not count these questions. (I consider this a natural approach - if some thread was bumped anyway, why not improve it.)
I found 9 questions bumped because of an edit or a retag:
198787
164783
77536
146288
143624
60123
201147.
178999
62203
Of course I might have made a mistake - I don't know of a better way how to do this than to go through questions manually. But anyway 9 questions out of 150 does not seem as a large number to me. (The fact that several old questions have new answers was more surprising to me.)