DRM or no DRM, piracy levels will be the same. The point is that as a game studio, they won't be spending obscene amounts of time, effort and money on something which gets removed within a couple of days, and even more importantly, will not annoy their legitimate customers and hamper their enjoyment of the product.
I remember the first Prince of Persia well, played it from a 5.25" diskette back in the day of EGA graphics.
Might just pick this one up to see how it compares. 