The companies that are doing it, don't recieve money from USED/Rental games they are losing a share there to what really should be theirs, also it was to help stop piracy or deter those who do it. It probably wouldn't be a huge issue if Piracy wasn't so big on all platforms.
Anyways besides that, it comes down to the Publisher & Developer whether they charge or not, EA usually does now, and THQ has been for about a year. But recently EA didn't with Crysis 2, not sure why but they don't have an online pass and the game is amazing. Its the serial number on the console =S.
Also one thing that would be bad is it is rumored that for Sony to stop Piracy they are going to include a code that can only be used 5 times with the game disc, if this happens you will pretty much have to buy games new which will be a horrible option for the gaming community.
I usually don't pay for the online pass unless I know for sure that I want the game.