Although I know that mouthwash isn't strictly necessary, there's just something about it that I love. Maybe it's because:
1) It freshens breath
2) It wakes you up
I don't really care that much about the germ-killing effect (with possible temporary dryness), though I hope it helps since I'm horrible at flossing (how do you floss your molars? I've never been able to do it :( ).
Although, you still have to be careful that the mouthwash you use doesn't stain your teeth (Chlorohexedine). I use mouthwash only 3x max a week because I drink a lot of coffee and tea.
What does make me curious is how come most people prefer to use a dilute version of mouthwash versus a concentrate. The concentrated solution is just a bit more expensive, but you get at least 3x more of the product. Sure, the diluted version is good for kids (who cannot be trusted NOT to check the label before swilling a mouthful of concentrate) and for travel, but the concentrate does it's job longer. I love the fact that you can control how hot your mouth will get by changing the amount of water you use. I just don't see why diluted mouthwash is more popular than concentrate.