I can't imagine piracy had much to do with it. For one thing, one of Micromancers' most popular MSX games, Children of the Night, is virtually un-pirateable to begin with, since it uses battery backup saving, which -- to my knowledge -- makes it impossible to properly emulate or play on a flash rom cartridge, as the game will simply freeze every time it attempts to read from or write to the battery backup.
But more importantly, piracy requires two things: a distributor with know-how to buy the game, rip the cartridge, and distribute it in public channels... and a willing audience to download that rip, play it, and spread it around.
I can't imagine there are many people who own an MSX and have the know-how and means to buy a cartridge game from an independently run website and rip it to a rom file who would also willfully and knowingly distribute the game to others. Like, this is a hobbyist community. Pirating old out-of-print games that you can barely get your hands on anymore and are no longer making anyone money? Sure. But pirating brand new games made by dedicated fans and sold for peanuts to a very small group of other dedicated fans? You'd have to have a real axe to grind with Micromancers to do something like that. Like, you'd have to be a very petty person with a real grudge.
And even if one were to assume that someone from Micromancers like, stole somebody's girlfriend, and that guy was now out for revenge... how many people are going to even be interested in downloading pirated Micromancers games? Not to slight their work, as they really are an excellent team who produce great games, but again... this is a hobbyist culture! We're not mainstream by any means. And I doubt most of the few of us who know about Micromancers would see a .rom file of Suite Macabre on some random pirate site and think, you know what? I'm not going to bother paying for this game that I clearly have the money to buy and an interest in supporting; instead, I'm just going to download it and play it, because I'm a cheap bastard! 
Piracy is a problem for AAA developers and mainstream, big-name game releases, but for tiny hobbyist projects like this, I'm willing to bet that if anyone DID pirate them, it was a dozen or fewer people, tops. Probably more like 3 or 4 people. It's not going to have been a widespread problem that would've led to the team disbanding.
-Tom
2500-5000 is very exagerated btw 
From my experience margins are closer to the 10$ margin, leaving it at 1000-2000, and then these large productions like Micromancers' are a team job, so, assuming 4 people, we are talking about $250-$500 per game (which is the right amount in my experience).