Then read and be enlightened.
Every class is made with weaknesses that can be exploited by another class, right? Let's take the classic sniper/spy/pyro troika.
With the original equipment:
- Snipers can kill pyros from across the map, but generally fall prey to spies.
- Spies can kill snipers, but fall prey to pyros.
- Pyros can kill spies, but get killed at long range by snipers.
Spies are scissors, pyros are rock, and snipers are paper.
Unlocks changed the roles of these classes. Jarate, huntsman, and the razorback makes snipers more able to kill spies. Dead Ringer, Cloak and Dagger, and Ambassador makes spies more able to kill pyros. Pyros... kinda got screwed, no big shifts in paradigm.
This makes snipers like scissors and rock, spies like scissors and paper and pyros like a rock and possibly a bit like paper due to the flaregun.
Spies and Snipers can fill two roles depending on the unlocks they use while pyros just become more of their role.
So what makes people mad about unlocks is that they're so used to either filling one role or being immune to another role, that they're upset that the roles can change. One class can change weaknesses and strengths to fill another role that a class used to own by itself. They need to embrace the unlocks and begin exploring the role dynamics that these changes bring about.