Very interesting to see the comments on here with regards to the debatable meaning of theft.
Those who don't think it is theft simply think that no person has been deprived of anything and therefore a theft can not have occurred. They conveniently forget about the artist (or rights holder) who is deprived of the fee legally due to them when a copy of their work is distributed.
What I really don't understand is why so many people are so content to deprive the artists they like of the funds they need to carry on producing more music. This seems a little like a snake eating its own tail, until one day pffft! One day there will be no more music worth listening to, games worth playing, movies worth watching, etc.