You must have got lucky playing 4 free mode. Most of the time I tried to play free mode it was like playing deathmatch. Even if they have friendly fire off they still get rockets and shot it at you.
As for 5, I don't think you get a bad sport if you blow up other players vehicles. You do have to pay for it. I had someone blow up my car, when I called to get it back, the guy that blew it up had to pay for it. You become a bad sport by leaving missions and stuff. I have gotten a $1,000 a few times for being a good sport. It really doesn't take long to rank up if you do missions and stuff. If all you do is hang out in free mode, you won't gain a lot of rank. I do think if you go into passive mode, they shouldn't be able to kill you in your car. Or blow it up. Paying $100 isn't a lot of money to make it like friendly fire and cops off.
Personally I like 5 a lot better. I like the online and how they are making it like MMO game. Much better single player story too.