This is a double-edged sword. If developers/publishers don't have anti-piracy measures to rely on (no matter how reliable/unreliable they actually are), they lose incentive to continue to develop/publish PC games. Piracy can potentially take a huge chunk of the profits. It's one reason why MMORPGs make the most money - you can't pirate subscriptions. Other PC games make a bit of money at first, then piracy eats away at the profits. I don't blame developers/publishers for being wary of that.
You can't compare an MMORPG to other games in terms of revenue. They have completley seperate business models. PC games make money at first but it is market saturation, not piracy, that causes the drop in ongoing revenue per title. The average MMORPG player will spend much more money over time due to monthly subscription costs. If you want to bother looking at the actual market data (most studio execs don't like facts getting in the way of business) then piracy does not actually hurt profits, it may even bolster them. Look at the record industry. During the height of the Napster file sharing movement the record industry was making record profits. Then Napster was shut down and DRM was added to music and profits tanked. Once DRM was removed and RIAA approved downloads became available then profits came back. The lesson that was, or at least should have been, learned was that digital piracy is driven by an unwillingness to pay for a product as it is offered. There are three important pieces there, Price, Product and Conditions.
Price, there are some who won't pay any price no matter what. These people would not have purchased the product to begin with, any resources aimed at stopping this group would be wasted. However there are others who would be willing to pay, but it is dependant on the quality of both Product and Conditions.
Product, pirates and customers both have equal desire in a product, this is illustrated by the number of illegal copies of Avatar vs those of Spice World there are circulating about. If it's not worth buying then it's not worth stealing. But how do you know if something is worth buying? Most consumers like to try something out before purchasing it, this covers everything from test drives to free samples of microwave burritos at the store. Once upon a time most games had demos that you could play to see if you liked the game before you actually purchased it. Then someone got it in their head to release "demos" that were more or less beta testing grounds which made consumers think that the whole game would be as buggy as the demo. Rather than going back to the idea of the demo as a chance to hook the gamer in the concept was largly dropped as a whole. If someone wants to play the game for an hour or two before they spend money on it they have few choices, ever more restrictive DRM schemes that ensure "only you can play your games" narrow the choices even further. So here we see where a pirated copy could become a sale that would not have happened otherwise. If someone won't purchase the game with out trying it first, and does not like it when they do try it then there is no sale lost. The issue comes from those who turn to piracy to get their "demo" and end up liking the game but never getting around to actually purchasing it. These are also actual lost sales because without an official demo they will never get to the point where they cannot continue without purchasing.
Conditions, part of the reason that Napster was so popular was because it offered every song as a single. There are, as evidenced by ITunes, many people willing to pay for a single song but not the rest of the album. This was an underserved consumer demographic that went to the only source offering just the product without the additional condition of having to purchase a dozen B-side tracks to get the one song they wanted. Every pirated copy in this group represents a lost sale, this is where the publishers can do the most to diminish piracy. If you want to play Skyrim without Fast Travel, wait a little bit and the mod community will help you out. Want to play without having to create a Steam account? You have no legal options. If players are taking the risks by downloading hacks and cracks from shady sources to use with copys of games that they legally purchased then the publisher has done something very wrong.