I use modules all the time. It like having a script or a novel already writen--I just have to doctor it to my tastes, which is a hell of a lot easier than filling a blank page.
Plus, it's such a time-saver using published adventures Stats are there. Maps. Background story. The whole she-bang. I usually spend some time customizing the module, though, to fit my campaign. My game runs like one big piece of life. The players find it hard, sometimes, to figure where one adventure stops and another begins. I play it out smooth. If I know where I'm going, say, three adventures down the road, I'll even lay in plot points that will pay off a month or so later. "Hey, remember when we came across that scroll several game sessions ago?..."
Sometimes I'll run a module fairly straight. Sometimes, I'll just drag pieces of it out and use it separately.
For example, in the game's last module, the players ended up skipping an entire encounter. No problem. I've keept it "safe", as they say in the Marathon Man. I'll just pull that encounter out and play it some other time--probably in another part of the game world.
I also make up stuff from scratch to play, but that takes so much time, making up the story, populating it with NPCs and items, etc.
If I had the time I used to have when I was in high school, I'd prefer making up my own stuff. But, since I don't have that kind of time on my hands, I much prefer published modules now.
In fact, when I'm looking at a new game to buy, I'll check to see how many adventures have been published. If the selection is nil or thin, I'll typically pass on the game.