I suspect that it was because there was a high number of complaints appearing and this did not reflect too well on SANParks management and tended to discourage first-time visitors. Whilst I would hate to discourage any visitor to visit our wonderful parks, I did, like you, find the threads useful in terms of knowing what not to do/visit. stay at/ eat at and so on. I think that although one can raise the topics in other threads, not nearly as many people will see them, and they will not be usefully together. I would also not like a first time visitor not to enjoy their stay because they were unaware of certain problems and could thus not plan accordingly.
Salamanda I am also of the opinion that it is done to limit the complaints in public, think Sanparks were taking strain from people complaining about the same things and about nothing being done about it, so they stopped the complaints in public instead of fixing the problem.
I do not believe a first time visitor will be put off and if they are put off it means it has got to such a point where it is then deserved. People understand a once off complaint, but repetitive complaints about the same thing are something different. I thought all the complaints from the site were forwarded to Sanparks relevant people anyhow, so I see no difference then to the official complaint or the forum complaint, they should both be treated seriously.
It could also have been valuable for Sanparks for eg
If a thread was started and there were many about take aways at Lower Sabie, Service at Satara and people could comment, you may get 10-15 people who agree as they also had a problem, but it may not have affected them to a degree where they would make an effort to fill in a feedback. So because they did not make an effort to fill in the feedback, it does not mean the problem doesn't exist. All it means is that there are a lot more people walking around unhappy about something of Sanparks. I feel people are more inclined to discuss it on an open forum in general conversation instead of a feedback form.
But these are just my opinions, It could all be above board, I just feel the opportunity for the info sharing is now gone and gone from a Sanparks point as well as very few people will take the time to fill in the form, they just wont use the service again. So Sanparks will think everything is cool and a person will be getting terrible service and product and just not using it again. But there will be new unsuspecting people daily so who cares????