Honestly i'm a bit fed up. What is the point of theorycrafting if the most popular posts in this thread are people jerking about and complaining about stuff they think will happen ?
I personally don't think that giving every scout a get-out-of-jail free card would make the game more fun or interesting, but I was wrong on other unlocks before (underestimating the mangler/overestimating the brass beast for example). There's only one way to find out and it is to actually try stuff out. Who knows, maybe the speed debuff that applies when the effect wears off will prove to be an interesting mechanic ? I'll admit that I didn't even knew that you couldn't block with the bonk.
I do think that unbanning it after a single invite-only tournament is a bit fast, since I really enjoy whitelist pre-season cups as they allow for every player, regardless of skill level, to give their input, but I understand the logistical constraints behind such a tourney. Lucrative's event had the merit of at least giving us a clearer view of what these unlocks are actually able to do.
Ultimately, I think we all play TF2 for different reasons. Some people might want to go back to the 2009 whitelist, where only the Kritzkrieg, Gunboats and Escape Plan were allowed, and maybe they would have more fun playing if that were the case. But I personally wouldn't. To me TF2 at its best is a game of endless possibilities instead of some sort of tactical RPS (subtle dig at Overwatch in a attempt to gain upfrags), and I think that most unlocks, even less-used ones are interesting as they offer at least another option. Some new options are simply not fun to play against (like the Vaccinator) and must be axed, but we can't really know without trying them first.