The importance of the combine is debatable. Watching grown men run the 40 yard dash in spandex is not for everyone. I don't think the combine can really hurt anyone because athletes who believe they wont perform well simply don't participate in the activities.
It does help players though. The so called twiners can carve out a niche for themselves and many a GM's radar go up during the interview process whether it be good or bad.
The Browns Jordan Cameron did benefit from the combine. Cameron was considered a Basketball player turned Football player who had one year as a starter at USC. He ran and jumped well at the combine and the Browns took notice.