Well the first time I heard of the model folder was as a fix to the warden buff that would instantly crash everyone in siege. I'd say that was a very valid reason to use it, as siege was unplayable if a single warden decided to use their buff. I recall the folder being openly disussed in the forums and used by a large number of people. It was literally the only solution to the problem, since the developers didn't do anything for a very very long time.
No one had a problem with it until people started removing barriers. That pretty much killed it as a legit workaround.
Also, how about adding more options to remove effects in game, that's a win/win for everyone.
Once the "Warden fix" removed that issue from Siege--three years ago, mind you--the "fix" involving the user-generated file was declared an exploit. It was no longer needed and, more importantly, it violated the ToS/EUALA regarding editing game files.
The real problem generated by it was that several "experimenters" discovered other uses for edited model files, to the detriment of other players' game experiences, along with giving players who used it truly unfair advantages. Of course, they disseminated that information to guildies and friends.
As for adding LEGAL (built into the client) options to remove effects in-game, that's purely up to Runewaker to develop. Make the suggestion in the proper forum and it will be passed along. Detailed descriptions of the changes requested would be very helpful.
I said previously not to use the exploit, and I meant it. It might take awhile, but we WILL catch those using it. The punishment(s) will be handed out appropriately, on a case-by-case basis. If you get caught, you will NOT enjoy the consequences.