I think wins do matter...
It isn't that they don't matter, nobody said that, in fact they are the most important bottom line statistic for measuring the success of a team. Repeat: a team. They are a poor measurement of a pitcher's achievements.
Say a pitcher throws seven innings and gives up one run. And next outing does the same thing. And the next. Those are good outings. But in the first game his team scores no runs. In the second they score seven runs before he leaves. In the third game they score seven runs all in the eighth inning. So he gets 1 win, 1 loss, and 1 no decision. All for roughly the same effort.
Or say a pitcher throws five innings and gives up seven runs. And next outing does the same thing. And the next. Those are bad outings. He can still get 1 win, 1 loss, and 1 no decision, all for roughly the same effort.
Or say he comes in to save a game, blows the save, and the team re-takes the lead their next at bat. He gets the win, for performing badly. If he had done his job he would not get the win.
Those are just a few of many examples of why wins is not a good measurement. Sure, over the course of a full season, more wins is generally better than less wins, and I think wins are important, just not THAT important.