In general, I would prefer that users ask for support in the thread which the mod is stored; why? you might ask. Well, others can then benefit from the help, others may have an answer and the user could get a faster answer and I really don't consider "support" on a free modification to be one-on-one kind of thing. Waiting for a reply from me for a question which has already been addressed or can be addressed by the community faster only increases the chances that you will be disappointed.
2 minutes for every PM can add up if every user felt that their question needed to be handled by PMs.
Why not just ask your question in the thread?
The problem that I have is that this is one of the only forums that get replies to threads in.If you look at un-answered threads, there's over 20 pages. I have asked in threads and they also get ignored. If a user is that ignorant, it doesn't really matter where you ask them.
May I also add that this is NOT a bash at the staff. I have said above how the admin's are very helpful. This is more of a thread that is where I am almost backing up the staff, in the case that some members need to do their own bit to improve vbulletin.org
Also, one of the PM's was to a moderator and was about vbulletin.org, not an actual modification