Still, none of these reasons ever prevented me from utilizing modules. Why? Because even early on I viewed most of these as simply 'starter' ideas for me to expand upon. Thus, even a crappy adventure can be salvaged and turned into something useful. While I found very few of the Star Wars adventures to be 'crappy', there were several that I thought were sub-par. For example, a lot of the adventures in 'Twin Suns of Kira' and 'Politics of Contraband' were pretty sketchy and even goofy (a starfish man wearing a fedora?). But in most cases the IDEA was sound. Thus, once you took out Starfish Fedora man (and some of the other goofy touches), the idea of a treasure hunt vs. several rival ship crews was workable, and fun. So in answer to the argument: some modules are crappy, my response is: only if you let them be.
Likewise, when a module doesn't seem to fit your campaign, there are usually ways to twist and modify it to make it fit. Use the module as a framework rather than an exact blueprint. In fact, even if the adventure DOES fit, its nice to put personal touches to link it in with your own campaign. For example, in the adventure 'Domain of Evil', there was a rather 'generic' opening where the players ship is ambushed by hunters and crashes. This was a bounty-hunter who I'd never used in my campaign before, so it didn't really have a personal feeling to it. So before the adventure, I ran a little scene where one of my recurring NPCs (Zardra) actually set up the party and put them in position to be ambushed. It was a small thing, really, but it helped to make this adventure feel more like it was tailored for the party.
When you really examine them, the first two arguments against modules pale when compared to the third—the pride of a GM in creating their own adventure. While I did run an awful lot of stock modules (I would even say that the majority of the first two years was primarily from module play) there is something enormously satisfying about coming up with your own idea. There is what I call the 'pride of creation'. It helps feed a GMs ego to know that they can point to something and say that it is theirs—especially when the players love it.
I can remember one instance of this in my own GM career, in the 'Otherspace III' adventure I wrote. It was a sequel and epic climax for the Otherspace 'trilogy' (as I saw it). I labored on it for weeks and I still felt 'unprepared' when I finally ran it for my players. But it came off spectacularly. Even recently, some of my players commented on just how much fun they had with that adventure. Yeah, it felt good that something that I did had that much impact. It fed my ego, just like it would feed anyone elses. But then reality set in, as it always does—I couldn't imagine always putting as much work into every adventure as I had into that one. The simple 'physics' of trying to run a weekly game for practically 9 months out of the year just wouldn't allow for that. Thus, I saw, modules as the fuel that kept my campaign going.
The fact is, that a written module becomes your adventure as you run it. Even if you don't change much of it, your interpretation and 'spin' can easily make it unique. And though I still get a kick out of making my own adventures, I don't feel any less 'creative' than any other DM for running pre-packaged stuff.