The markets that we're targeting with this network are not a secret. Most of the markets are listed right on the home page on the section that says "PilotEdge is for..."
I'm sorry you're frustrated by the lack of traffic at the times you've flown. Most evening in the last two weeks have seen pretty healthy traffic levels, where the controllers are talking quite frequently. As long as you're hearing a controller talking and having to listen for your callsign, then I think the network doing as well as can be expected. Would it be nice if every channel was worked by a different controller? Yes. Would it be nice if every channel had a reasonable number of pilots on it? Sure. Let's talk about why that is impossible to achieve.
The 'traffic density' argument is perfectly valid, btw. The real world National Airspace System is able to house over 5000 real world IFR flights, plus thousands of VFR flights all at the same time, and the reality is, there are tons of places that are still a ghost town even with those huge traffic levels.
Opening up more airspace doesn't necessarily bring high traffic density in the ONE area that matters...which is where YOU are flying. Do you care if an airport 2000nm away is buzzing with planes? You shouldn't, because their presence doesn't affect your flight one bit. All that matter is planes being close enough to you that the controller you are talking with is also talking to them. So, yes, I stand by the traffic density argument. And yes, there are times the network is quiet. I make no apologies for that, I can't force people to fly. All we can do is provide consistent service and try to get the word out there. I'm working on saving enough funds to try some additional retail marketing strategies, but I'm not sure you appreciate just how much money it takes to run the company as is. I can say that we are working on securing deals with commercial clients that will bring larger volumes of traffic to the network on a regular basis (although we'll have to add additional concurrent controlling positions to accommodate that).
That actually brings us to issue #2, which Ryan eluded to in his post. Expanding airspace means having more controllers online at the same time (just in case you were hoping that we could expand without having additional controllers online). Pick any reasonable pay scale for the controllers, then do the math on 15 hours a day, 7 days a week, 1-2 controllers per facility, 20+ facilities. You instantly have a liability of many tens of thousands of dollars per WEEK in payroll. Even with money the bank to support that for a year, I simply don't think the market is large enough to support that burn rate. We'd absolutely have more customers, sure, but the traffic density in each facility would be worse than it is now, by and large and the increase in subscribers would not make up for the massive expenditure. Ultimately, the venture would operate at a loss, long term, unless you charge MASSIVE subscription rates. There's zero evidence that the sim enthusiast market will support 3 figure per month subscription rates.
With more controllers comes more management and training costs, too.
One more thing to consider, it may be a warm and fuzzy feeling to see a bunch of jets going from EWR to LAX at FL340, but unless they're really close together while they're enroute (which not going to happen outside of events), the ONLY thing you're going to hear is ONE check-in per center sector of, "Center, UAL123, level FL340." "UAL123, [ARTCC name] center, roger."
For the markets we pursue, the size of the coverage area isn't critical to the success of the venture. It would be NICE to have, no question, but it would be a toxic anchor that would drag the company down within seconds.
That is as direct and transparent an answer as I can give. If you're a sim enthusiast and you're feeling cramped/bored by the coverage area, then this there are other places that would ultimately be better, as they offer the promise of a larger coverage area, albeit on a random basis (in terms of controlling quality and schedules).
We just did get a little bigger, btw, we added SFO to the coverage area, doing it in such as way that it ultimately didn't cost the company any more to operate. The reality is that there are very few expansions we can do of that nature, though. We simply can't throw more onto the heap of responsibilities associated with the existing controlling positions. I'm grateful the existing controllers accepted the task of handling SFO. I'm glad that I control here as well as run the company, though, because being on the scope gives me a good feel for what I can reasonably ask of the controllers, and where that line is. Adding SFO is one thing. Adding more facilities, though, while maintaining the level of quality that we offer is something entirely different.
I can understand the reasoning behind most of your post, but I disagree that "PE is a ghostown." That's a massive generalization. There are times when it is...and there are times when it isn't. There's also a connotation there that it's 'dead', is not providing value, and/or is not sustainable. I would violently disagree with that (if that was not part of the intention in choosing that word, then disregard.)
I also want to point out that even when the network is quiet, you can still fly and have a great training experience. I can't tell you how many times I've done real world flights where I've called for radio checks every 15 minutes just to make sure the radio is still working. It's not always full throttle mayhem out there

Our goal is to provide professional ATC for simulators. We can't and don't promise real world traffic levels.
I would encourage you to think about WHY you want to fly with ATC. Our primary differentiation from the home user perspective is that we are the only network that provides ATC on a daily, recurring schedule with this level of quality (if I'm wrong, let me know). Expansion comes at massive cost with very little additional training value. The potential market size of sim enthusiasts who are willing to pay for ATC is not big enough to offset the cost of running that business, even if we had the marketing dollars to get the word out there.