It has very little to do with sales, or at least I don't think it's the sole reason. FIFA & NBA 2K are worldwide sellers, sure, but they are also WAY bigger targets for piracy for that very reason. Not every country has a DMCA-style law to prevent piracy (not that the DMCA means jack **** to pirates anyway. An unenforceable law that only hurts legit consumers), and not every country allows for full EULA enforceability like the US does. Hell, Idk if the EU allows for EULA's that supplant consumer law. It is also important to note that NBA Live hasn't had a PC version since Live 07, which would fly against the argument for a particular sport's worldwide presence and influence.
The bottom line: EA is a very petty company, in every way. For me, it breaks down into a few simple reasons:
- Modding. There is a HUGE Madden 08 PC community that not only has added the cosmetic stuff like updated uniforms, rosters, & equipment... but they also add new animations to the game, like laterals and extra juke moves. They even found a way to add practice squads & IR placements freeing up roster spots. If EA was petty enough to destroy the football market when they knew & acknowledged (in court, no less) that their product couldn't hang with the competition, then they are petty enough to avoid PC due to their inept devs at Tiburon being shown up by people with less time & less resources, but plenty of passion. But even simple things like removing DRM (because DRM only hurts paying customers; Pirates are always ahead of the curve). EA knows that PC gamers know their way around.
- Pricing. What a console gamer will pay for a game is drastically different from what PC gamers are willing to pay for the same game, especially one with dubious quality like Madden. With the advent of Steam, the perception of the price to value ratio has changed PC gaming dramatically. And with that said, I question as to whether or not PC gamers would be willing to pay $60 for Madden as an Origin exclusive. FIFA is a different thing because of its worldwide appeal, but even then, there is a gulf of quality that exists between FIFA & Madden, depending on your perspective. Even at $60 + Origin, FIFA gets away with it because it's a better product.
- Lack of monetization options. This correlates to the first bullet very well. There are games on PC that have save editors & executable hacks that can add anything to a game. For instance, the "credits" currency in Mass Effect 3. I can download a save editor for ME3 right now that not only changes in-game content, but also allows me to add or remove in-game currency (I could also download Cheat Engine & look for parameters that control certain in-game elements, then change those elements in real-time, but it's a lot harder to do that). Or in terms of cosmetic items, currency, & DLC sold via microtransactions (like the EA Football Club stuff in FIFA). If any of that is already locked within the game's code (like a certain Capcom game), I can just look in the packaged files, or wait for someone to hack those files and finds a way to unlock those items for in-game use. Or, if those elements have to be downloaded, I can just wait for someone to upload a torrent that contains all the DLC & microtransactions, or wait to purchase a game until there is a Game of the Year edition of a game, or a Steam sale of a game + DLC marked at 70% off. All of the above mean that EA really has no feasible way to monetize PC games because the workarounds for that are so relatively easy to implement/carry out, that piracy methods are seen as a drastic last result that most PC gamers would like to avoid just out of respect for the developer.
I just want to point out that just because the above methods exist for PC gamers to use, doesn't mean that all PC gamers use them, or that PC gamers are pirates. It's just to illustrate that PC gamers have numerous ways to avoid any inconveniences that EA would throw at them. And EA knows that. EA (and most other publishers) know that any kind of business models & strategies that work on console would be ruined by the PC crowd. That's why consoles have such a large focus from publishers in the first place: more control over both the marketplace and its consumers, as well as piracy being way less of an issue.
In fact, I would go as far as saying that EA only deals with PC gaming because they have to; for certain genres, it's too big to ignore, especially on the online gaming front. That said, it seems like they avoid it with their most precious cash cows like most America-focused EA Sports titles...