As long as people make their intentions clear at the start of the run, I see no problem with this. It's your choice to stay in the group or not.
Don't like the rules of the group? Don't join. It's that simple. I don't understand why you're making a huge deal out of it.
Reserving an item makes it harder to fill out a group though, so I think it's a fair trade off for people who want to reserve an item.
For those who don't like reserved items - read this again and again ... and again.