AS WELL as the attitude of Planet Quake and ID Software. I think taking money for a mission pack with the aim to add something the original Q3 wasn't successful at doing is not fair. Since the release of Q3A we never really received anything from them except for the endless point-releases and a couply of CTF maps. Instead, all we got was the software and the necessary fixes and ID in return got lots of cash. While not having an impact on the community's growth since it's so massive it gives people the right to bitch about things.
People have to pay for it, so they DO have the right to bitch about it.
Planetquake is even supporting that. The one of the customer, or the one producer. If Epic had bowed to the capitalist gods and charged for it, no one would be bitching. The purpose of a company is to make money - you have to compensate the employees for the time they put into the game. I don't know anyone at Epic, so I can't say why they chose to release the add-on for free.