First of all thanks to the OP for creating this thread.
I also grew up with Master of Orion. Can't really tell if I prefer the original one or the second installment, certainly not the third.
If you look at Brad's Stardock Customer Report 2011 I think you have part of the answer of why he's afraid to buy MoO from Atari and make a sequel, or a re-imagined version (it didn't need to be MoO4, could be Master of Orion Universe or another name). Brad states (or at least he's afraid of) that he believes that "we" are finished.
"The counter-argument to making complex strategy games with high production values is that the demographic for these games, males 25 to 55, does not have a long-term market future" ~Brad Wardell in Stardock Customer Report 2011
Brad states that he thinks 15-25 year old gamers are only about FPS and "playing on rails". Well, I thought it was Stardock's mission to keep complex and excellent strategy games alive and well. Brad then softens by saying:
"Stardock’s position is that as the new 15 to 25 year old demographic transitions to the “older” demographic that their gaming requirements will transition as well" ~Brad Wardell in Stardock Customer Report 2011
So, there are at least some mixed feelings on Stardock's (Brad's) mind about the future of strategy, PC gaming and complex gameplay overall. They are more or less in the same boat as Firaxis Games in my perspective (these are probably two of the game software companies I like the most).
So, behind all the excuses and long-shot statistics arguments I think Brad wants to make MoO4 (badly) but I think he's afraid to (he or his mates at Stardock). "It can't be done Brad, there is a legion of MoO starving fans out there that will kill you for breakfast just for the pleasure of it. They will always says MoO2 was the best no matter what". Wrong. It's hard to do a competent sequel, yes, but I think it can be done with incredible return potential.
Arguments to make MoO4 and be successful:
1. Established mature fan-base. We are PC gaming veterans. We love strategy, we love you (for GalCiv and Sins), we are a lot and we'll help you make the best game possible (as we helped you with GalCiv). We will not let you down. There are (and ever will be) jerks and morons everywhere but in this case the community is just too strong to be permeable to absurdities and nonsense.
2. Almost no marketing will be required (and this fits Stardock culture well as I read from the customer report). Just release a MoO4 teaser video on youtube and all the necessary marketing is done.
3. Motivation on your dev team (and everyone else I guess) can't get higher. "We're making the next Master of Orion!!" It can't get much better than that.
4. The last series installment was a complete let down, the only way is up.
5. MoO2 was released in 1996! Imagine what you can do with today's technology.
6. You're Stardock! You say that you're "focus[ed] on making cool stuff" and that you see an opportunity to cash-in through the "dumbification of games [makes room to] developers who are willing to create games that cater to individuals who are interested in a complex game experience but also want high production standards." and that you're "interested in developing games that appeal to men and women that involve considerable game play sophistication."
You're meant to make MoO4. You know it, we know it. So, what are you waiting for?