I really think that unless you were in that situation, in that specific time in history, you can't say whether those that decided to avoid the draft were "right or wrong". My dad was in ROTC when war broke out, and actually had been given his orders to move out with his platoon; while waiting, he found out his wife was pregnant, and he was assigned stateside. I love my father dearly, and respect him even more. We've actually talked about his experiences in the military a lot lately, as I finally grew up enough to really understand what he did. He always told me that he respected other people's right to decide to avoid the draft, but given the way he was raised, he had always believed that when his country called him, it wasn't his choice to decide whether the battle he was to be sent to was right or wrong, but to fulfill the promise he made when he enlisted. He lost many of his friends in the war, and lost many more of them following the war. He keeps in touch with a few of them, but I think his feelings about them are bittersweet - he fully expected to go and was ordered not to, while they didn't necessarily want to and were drafted.
Obviously, his situation is much different from people who were summarily drafted - he volunteered for duty, and came from a very long line of military officers, so his background probably wasn't that of the typical Vietnam soldier, but from what I understand about that period of time, you just can't judge what was right and wrong. A lot of people felt the government was hiding things (and they were), and had every reason to feel like they were being pulled into a conflict they had no business butting into. I'm not saying the war itself wasn't a just cause, but the government just never communicated what was truly going on, and people's perception of what was happening was skewed. There was just an overall feeling of mistrust, that the government was deceiving people - and with the media whipping the anti-war movement into a storm, I think a lot of people who wouldn't have balked at serving in any other war at any other time just didn't see why they should sacrifice themselves for the sake of a country they knew little to nothing about.
Personally, I fall into the camp that says if you're drafted, you go, but I was raised in the post-Vietnam era and it's inappropriate for anyone who wasn't there to say what others should have done.