I agree with the bolded statement, and it is exactly why I hate the when people start talking about the regular season being devalued, or it being the greatest thing known to man. It's not. The regular season should put you in position to play for a title. That's what playoffs are for. The regular season seperates/identifies the best teams, the playoffs pits them against each other to see who is the best of the best. The issue comes down to whether the system we have now does this well enough, or if a playoff would do it better. I support the latter, obviously.
You're making it out as if with a playoff system would have three and four loss teams throughout it, when this is not the case. I think most people who favor a playoff support having it exclusive only to conference champions, with few, if any, bids for non champions. In this case, the most losses you would see a team with is probably 2, unless an upset occurs in a conference championship game, or there is a mediocre conference, where the champion has 3 losses.
Therefore, losses are still just as devastating in a playoff format, especially in conference play. The worst case scenario would be a 2009 Virginia, who had an atrocious start to the season, but still had a chance to win the conference. However, they would have to win the conference for any hope at the playoffs, because there would be no way they would get an at large bid.