KneeTheCap: This is actually a good question. I never understood companies not selling their products all the time. I mean, does it cost them to keep their games available on GOG, for instance? Shouldn't they just keep their whole library of games available for purchase constantly?
Some big publishers may feel:
- older games for a nickel may cause price erosion, also for their new titles
- newer games have higher margins, so they'd rather see people buy their newer games instead of cheaper, older games.
- overall they may feel the resources needed in order to "re-publish" an old game for the small(?) profit margins isn't often worth it. Unless someone like GOG or Night Dive Dave whatever comes to them and does the work for them "for free".
- if there turns out to be high demand for some older games, maybe they feel making a hires remake of it will make that demand even higher, and allow them to sell it more expensive, than if they'd just re-publish the original. Especially on consoles, they seem to resell lots of earlier games again as remakes on each new console generation.
I recall reading articles of EA pondering about this quite a lot, ie. some "alternative" venue for people to play older, classic, EA games. Somehow I read that that maybe they'd like similar system like PS4 apparently will have for older PSOne and PS2 games, ie. you don't run the old games locally on your PS4 anymore, but stream them, akin OnLive.
But at least so far EA seems to have allowed their older stuff to appear on GOG, luckily. Maybe they ditched those "alternative" plans.