We saw your suggestion in the other, correct, forum segment last week:
http://www.managerzone.com/?p=forum&sub=topic&topic_id=11295410&forum_id=13&sport=soccer
Activity really isn't as bad as it was about a year ago, heck when I returned to the game properly it was practically dead. I know there's still not a great amount of activity but... it has been much, much worse (don't know if there are stats to confirm this, would love to see them if there are).
Also keep in mind there are 4000 users online
worldwide, a lot of those 4000 might not like to interact with the community and just want to play the game... and I think it's fair to assume a big percentage of the more active users won't know English as it's not their native language, so a large chunk of the activity is spread around the other language forums.
Private messaging doesn't seem like a bad idea but, within ManagerZone it seems rather unnecessary, when it's simple to use other social media sites to privately contact certain users.