As a software author and working in the software industry, I obviously have a certain bias against piracy. But really, I don't think that matters. As a user I'm against piracy for purely practical reasons. These are some:
SUPPORT
When you buy software (at least from the better developers), you also get support. For those that really need to use the software and rely on it, there's just no substitute. Some developers offer support packages, upgrade insurance, or similar add-ons for their products, and they're often very worth buying. In general, a lot of them cost 20~30% on top of the cost of the product. Now, if you seriously need the software, then that's often a small price to pay for it.
RELIABILITY
There's a well known audio company that built-in some anti-piracy measures into their software - when it was cracked, the output had pops, hisses, and other unpleasant noises. But just enough to make it unusable.
When you rely on software to do it's job right, often cracked versions won't quite measure up to required standards. That can be for any number of reasons. I know some authors allow cracked versions to operate for a while and then they will suddenly stop. Some redirect to an anti-piracy page.
RELATED - BUT A BIT OF A TANGENT
I got my main machine back up. It was down for about a week. I did everything I possibly could to fix things and wasted a lot of time. Basically, the DVI port on it went bad or something. It was a real show-stopper as the screen was 100% black from power up to forced power off. When you really need something, and it goes down, that kind of trouble can be almost catastrophic.
The point there is that I rely on that machine for a lot of things. While I do have backups, they don't help much when what I need is a configured machine with all the settings and tweaks.
The same goes for the software I use. I can't afford to have it not work, so it just makes sense to spend the few dollars it takes to get something I can rely on.
And there are free alternatives for a lot of things. Commercial versions are often better, but depending on what you need, a free version may do the job perfectly well.
Anyways, just a bit more blathering on about stuff there.
Cheers,
Ryan