This doesn’t make a lot of sense to me. You say that coming up with cards isn’t difficult. But if a card is too complex, or redundant, or uniteresting, or uses a linear mechanic, then that is a bad card. So what this boils down to is that creating good cards IS difficult. There are still fresh, simple cards left to make. Not vanilla cards, but simple ones. The easiest way to make more simple cards is to introduce a new, nonlinear mechanic, which is again difficult—but not impossible—to do.
Well it's not that complex cards are bad; there are complex cards in most of the expansions. It's just that at a certain point the expansions have too many complex cards. Now I have blown it; I have, in my effort to please expert players (he said, not actually passing on the blame), tried to make cards as well-balanced as possible even though that meant making them too complex (again I will cite those Hinterlands cards I've singled out). That's an issue, that the expert players are less happy with the simpler, weaker/stronger card that casual players would prefer.
I have already done the experiment of "this is a good place to stop, wait I have to make another one." That set is Guilds. It exists only to come out between Hinterlands and Dark Ages (though it didn't); it completely postdates Dominion being published. I picked the most promising (most likely to produce good cards easily) ideas from my list and made some cards for them. It ended up taking a couple cards from Dark Ages (Journeyman, Advisor) and a couple old ideas that I hadn't fixed up yet (Taxman, Soothsayer) (Soothsayer shouldn't have the "if," there I am seeking approval from playtesters to the end). And it worked out fine; I wasn't somehow unable to make it.
If you loved Guilds then man the idea that I should stop making expansions must seem less compelling than ever. I am certainly pleased with Guilds. It is nevertheless more complex than I would like, it strongly demonstrates the diminishing returns issue, and a spin-off would have been better. Even if there's a non-linear thing left to do, a spin-off can do a linear thing and that can be good; a spin-off automatically gets new vanilla cards, not just simple enough to live with but extremely simple and yet still compelling; and a spin-off has no diminishing returns at all.
Here is more on the diminishing returns thing. Which expansion has sold the best? 2nd best? 3rd best? Well maybe that's not fair; Intrigue has been out the longest. Which expansion sold the best in its first year? 2nd best? 3rd best? 4th best?
You can just line them up by release date (skipping the small sets, which do worse). People stop buying them eventually; foreign publishers stop publishing them. They've got enough.
I mentioned this to the Making Fun people, while explaining why I wasn't making more expansions. One of the guys immediately said, yeah he had played a thousand times with his kid, but he had Cornucopia still in shrink, and didn't see the point of buying Dark Ages until they had gotten some value out of the last few sets he'd bought.
I am going to hazard a guess that you wouldn’t make those cards anyway, not because they’re actually bad, but because they wouldn’t occur to you.
I prefer to think that I would think of enough of the simple ones, and leave it untested. You can make complex cards for forever, so sure, I might never get to whatever corner there.
I made a bunch of homemade Magic expansions, and at one point aggressively looked for new mechanics. They do stuff I thought of all the time; there is plenty left that they haven't done, but they keep making cards, they will gradually whittle that list down. I guess that's not as relevant as it sounds; maybe I am just as uncreative as Wizards, and someone out there could blow us away.
If you have tons of great ideas for innovative cards for a game with rules on cards, I bet you can make your own games. It's good times.
• It potentially opens the floodgates of fan card submissions. Maybe you already get a dozen emails a day from people submitting fan cards and this is a non-issue. I have no idea.
I don't, hooray.
• Wanting to be the guy and getting to. I think this is reasonable.
I do want to be the guy and do get to. I'm not sure we do promotion well enough for a card design contest to do much for us.