You don't have to but it can help. I have written about how I like randoms and the anonymity of it all and being alone in a crowd , but there is something to be said for liking your group mates.
A few days ago, I queued for a PuG i was tossed into Scarlet monestary graveyard, the tank had left after the hunter pulled the whole room with the first boss. In a rare moment of weird clarity and skill? I dunno normally we would have all died (zoning is disorienting at least for me) I recognized the healer from eariler in the evening( she had been nice and patient with me) I bubbled her grabbed all the mobs layed on hands on myself and amazingly we all lived except the hunter he deserved to die ( healer gleefully whispered me of her joy at his passing) things went nicely from there , the hunter left to terrorize other PuGs after expressing his anoyance at the lack of heals directed at him, he was replaced by another hunter.Anyhow to continue the story we all chatted a bit after the whole "OMG that was that was crazy fun" The healer asked me to re queue with her all but the warlock left and we did four more randoms, the replacement hunter was sorta random with his shooting things but since we had bonded and started being chatty and joking in group he was gently chastised shaped up and even though the mage fell off a ledge in razorfen kraul no one got mad and any mistakes were corrected and weaknesses accepted ( the rogue we got had really weak DPs ) no one cared, no one called names( there was some advice about his lack of need for intellect and spirit but it was polite) so when we got the armory with at least two members feeling like they were too low it went fast and smoothly because people communicated at the end of the evening people sadly said how they wished for cross server friends and we parted ways probably to never meet again.
You are wondering what is the point I am making, I met this healer earlier and thus felt a feeling that since she was nice then I felt like I should give my very best effort and somehow bypassed my usual panic at coming in on chaos. This was also the case in the past when I had a tank I really enjoyed playing with we pulled off some amazing feats, at times when DPs were screaming and say Give up we will all die we survived. It was fun people laughed moved on and had fun, but the thing is we cared, we liked each other there was a sense of what happened mattering. With friends or decent folks at least there is a desire to push oneself and do more then just good enough to test ones limits to take chances, if you are with judgmental jerks you have no desire to really try hard you just want to get it done with and fast. If you care about the people you are with you do better you feel like it matters more to succeed, not that I don't try, even for annoying people, but more that you can rise to very amazing if you really care.