Unfortunately the answer is probably yes because sales of even the most successful software are small compared with other platforms. Lossing even a few sales due to piracy hurts. I think with RISC OS this becomes more personal because of the small size of the market and because many people actually know the developers.
Piracy seems to be social acceptable to some people and that is a real shame. Lets make piracy unacceptable and help those people who spend their time and effort developing for RISC OS.