I hear you, and I get everything you're saying, and... for what it's worth, the idea of the number of polys and textures and the filesize involved... I don't even know how enormous that would be. I don't know if you created all the assets, or if they're licensed, and there would be issues with that. I know there would be a lot of challenges and hurdles, no matter what.
And yet... I really want to add my name to the list of people who'll buy it if you ever include it.
Buy the ability to export, I mean - maybe as a paid add-on, to make it a little more worth putting in the dev time, once you have some to spare? - I'm absolutely buying the 'game' as it stands. Even if the only way I can get art out of it is with a screen shot, you deserve huge support for this. :)
I first heard of it less than fifteen minutes ago, and I knew I was buying it halfway through the first intro video I saw. And the first two questions that popped into my head were "I wonder if you can import?" (then I saw the 1.4 video and rejoiced) and "Wow. It'd be amazing if you can export, but there's no way... Right?"
Then I saw this thread, and I had to create an account to reply before even buying it, because I think you're maybe missing it's potential as an art tool. Process is so important to creative effort. Yes, flexibility and creative freedom is important, and I can make a much wider variety of things in, for instance, Blender. True. But the more freedom and flexibility you have, almost always, the more complexity you have. It takes longer, and there are more opportunities for the process to get in the way of your creativity.
Maybe I'll feel different after buying and playing with it, but from the videos,it looks like the -no pun intended - flow of creativity is just so easy and pure, I'll be really, really surprised if it doesn't become one of people's favorite ways to create.
Heck, do you want to know where I heard of it? Someone is offering a tutorial on how to use it for sale ($19.95 US, on sale for $13.97) on an art market website that gets about 2 million hits per month. Obviously, you're enjoying a lot of success already (though "enjoying' might be an optimistic term - it's got to be a little overwhelming, too!) but I think this is going to be huge. :)
Who knows where it'll go - a community of artist/users producing content optimized specifically for it (sign me up) seems very likely, if you allow it. Even by version 1.5, this is already effectively what millions of users were dreaming of when they bought software like Bryce and Vue and a dozen other programs. I mean... My god... You know how huge this is going to be, right? My head is spinning with how many people I have to tell about this, and in what order I'm going to tell them.
If you need a hand, at very least a beta tester with 25 years experience, including a lot of paid, in-house testing, I'd be happy to contribute.