The reason that people declare it stupid is because it's been discussed SO MUCH, and literally all of these ideas have been shot down one way or another--except for the "send someone a siege" option, that one is considered kind of neat.
The main obstacle to the 'send a siege' is that all critters in DF exist as a part of that region, and you'd have to chop that part off of the new siegers. It could work, but it's dramatically -sideways- from where DF is headed at present. DF has its mission statements, and multiplayer isn't anywhere in those. DF is heavily planned out in terms of cores and reqs and stuff; multiplayer just isn't anywhere in the plan.
PBEM on the other hand is pretty demonstrably not fun. It's not even hard to see why. Look at community games, how often do people fail to take their turn on time? At least 1/4 of the time on anything long running. So you can't guarantee that people will keep playing. What do you do then? You can't stop the game to wait for them. But you get all kinds of problems if one player was depending on another's exports, etc. What happens if you send an army to a player who quits?
Also what if two players have radically different FPSes and goals? One's making a megaconstruction on a massive 50-z-level waterfall, so they go a season a day if they're lucky; the other is in a 2x2 area.
SimCity 4 played around with an online PBEM feature, where a bunch of players would take part in massive region games. They just had to accept that each player ran at a different speed...SC4 was built for that, you could play one year in one city, a hundred in its neighbor, then come back to the first city and it's still just a year in. I can't see how DF could possibly work like that. People, artifacts, etc. couldn't easily be shuttled around...Constructing new sites to bring new players in would be difficult...
Essentially it would be a re-imagining of DF from the ground up, and it would be simpler, it would be lacking a lot of DF's detail. It wouldn't have a lot of what makes DF DF.
So, I think you would more want to make a new game from scratch.
ok so it's a bad idea, still, i have in all the pc's glory, power, and history i have yet to see an RTS MMO that isn't some website. personally i think dwarf fortress would be an excellent choice to be the first.
This is because RTSes are competitive, and very speed based. Over time you become powerful enough to squish everything, you exploit all resources around you, and then you hope you're stronger than the other player. How could this possibly be fun? Even heavily economy based RPGish MMOs tend to blow--I've played some online games where you can fairly easily set up a large base, but then you end up dominating everyone around you who doesn't have one...
The only way I could see a "multiple unit MMO" being any fun is if it was a small squad that follows normal MMO rules, IE, no permadeath, not generally growing in size.
Uh oh. X-Com Apocalypse the MMO, where you can control around 6 or 8 people in real time tactical. I think thobal is on to something.