The reason you should use a module is because someone else much smarter than you has figured out the stupid details...

Not always smarter -- just less lazy :)

In other words -- the wheel has already been invented, and the wheel is found to be good. But wheels are simple, and you could probably build a wheel, but you are building a car instead. You should never reuse square wheels, of course. But the part about not having to deal with 'stupid details' is absolutely right. It's all about not having to worry about stuff that you know you could re-implement (like wheels or spark plugs -- Lambourghini doesn't make spark plugs, do they?).

Then there are Damian modules.... *sigh* ... that's not about being less-lazy -- that's about being on some really good drugs -- you know, there is no spoon. I like those best. Ah, what a good job...