I absolutely would not leave unlocks up to democracy, especially at this point in time.
There are (apparently) 135 stat-unique weapons in TF2. Out of all of those, I think I can count 6 unlocks (Pain Train, Gunboats, Crusader's Crossbow, Kritzkrieg, Ubersaw, Escape Plan) as some sort of useful utility to warrant frequent usage that isn't completely off the wall. There are other unlocks like Chargin' Targe, Eyelander, Wee Booties, Force of Nature, Direct Hit, Concheror, Liberty Launcher, Righteous Bison, Black Box, Shortstop, Scottish Resistance, Overdose, Vaccinator, Blutsauger, Buff Banner, etc that simply don't see a whole lot of usage either because the item doesn't do enough to warrant using it for an extended period of time or that it would just be better to use stock. Then we have what I'm going to call "community questioners"; weapons that have split the community in different sections concerning the weapon's balance such as the Quick Fix and Loose Cannon. Let's total the weapons I've mentioned up:
6 frequently used "safe" unlocks
15 niche unlocks
2 "community questioners"
=
23 weapons
That's just for the standard 6s classes, and those are just the most frequently used/talked about weapons when we do talk about them. There are still outliers like the Market Gardener, all-or-nothing weapons like the Loch n' Load (although Benroads and I in our autismical behavior did a little testing on this and it can do stupid numbers even with damage spread off), and THEN we have weapons for utility classes like the Backburner, KGB, and Cloak & Dagger (pyro, heavy, and spy respectively). At this point in time where the community population is shifting, I don't think it's at all wise to individually test each and every weapon we've got (because that actually does get complicated) nor do I think it's any better to leave weapon pick/ban decisions in the hands of the majority, let alone on a game-to-game basis. Hell, if I had my druthers we'd be testing vanilla 6s in comparison to cinnamon (vanilla + paltry useful unlocks) play instead but eh.