Who is currently defining the thread's names? The GMs? NO - the users are doing that.
The GMs may update an unarppopriate name, exactly like what they would do in case that this suggestion will be implemented.
That is their role, and it would not be changed.
then we don't need it right? ;)
As you noticed we are very cautious with that, cause it usually leads to more confusion then makes things easier for the user. So we change inproperiate thread names, or bad names of "long term" threads like stickys. Other changes like that are very rare.
With the changes, we would had a list to go through with peple who changed their minds, make a typo and people maybe spamming this list, since they are undecided or don't see a reaction in time.
Maybe to put another though in it, the forum i know where this is possible allow it in the first 15 minutes when nobody answered in the thread yet. This is enough to correct typo, without confusing people where they had posted something or extra work for us gm(yes this time you can say it is egoistic)