A lot of the reason for their popularity is cost. Disposables are dirt cheap. There's little upfront investment. Most people who can't afford a computer (and therefore would probably not spend $200+ on a picture frame) like that.
So right away, I'd just not worry about lower class families. You aim gadgets at middle class +. I guess my argument is that I don't see much market for a $200+ digital frame amongst people who don't have broadband. There are probably a number of people who have broadband but not wifi who might like the product, hence my suggestion to offer a bundle with a cheap, preconfigured router. (Supposedly only around 40% of broadband homes have WiFi).
I know what you mean about assumptions, but startups are all about making them, building toward them, then narrowing down as you collect feedback from customers. There's simply no way to collect the relevant facts, you have to start from assumptions. They could maybe do some market research, which is slow and expensive, and at least narrow down the assumptions. Or they can just aim their product at the people who can afford it and are likely to want it, and work from there.
So if I were them, I'd focus on building a kick ass wireless frame. Most people who have digital cameras and have experienced sharing them online will probably get it.
But WiFi is really a very optional thing for now.
I'm not saying you're wrong, I strongly believe in focusing a consumer as tightly as possible in the beginning, and since he is dealing with a tech crowd here, he can make wifi a requirement.
But all the same, I don't think WiFi is as spread as you think. Imagine an iPod where one can transfer the music only by WiFi. Or an iPhone. That's a bad idea, is it not?
I'm not saying my sample is more accurate than your, but I am saying I have observed the opposite effect. There is probably some middle ground, the question is where the real statistic lies. And if one is willing to bet a business on that.
I really dislike assumptions. I like to treat facts as assumptions that have not been disproven yet, and that's why I argue this point - don't take it personally!