Upload & Sell: Off
I agree with your sentiments. I think that the biggest issue is that most programmers aren't photographers (opposite sides of the brain and all ).
And if somebody did come up with what they wanted (wrote or had somebody write software for them), then it did exactly what they needed it to do. Now, to make more money, they pawn it off as their workflow.
When I was looking 10 years ago, there was ED and another... can't remember and they are gone now, I think. So we wrote our own - highly automated, very simple to use from camera to customer to cashier.
However, from there, we do the editing and printing. We though about giving simple options to the customer, but the truth of the matter: They aren't photographers, we are. What do they know about editing. They want to buy a photo. Even as simple as you may make it, there will be some that don't get it - that ties up a person and that station for as long as it takes to teach them how to print there photo. Depending on your market and your events, you may or may not have the luxury of extra staff and time at stations to commit to teaching customers how to use software.
In our case, we have over 100 viewstations, but well over 1000 customers per hour to service. What we've learned for our fast paced events is that selling onsite is the key, not printing (we used to print onsite for two years, after stopping, we noticed no difference in sales, just less costs). There are plenty of others who would counter that printing onsite is their key ingredient - which I believe would work for events that have time to mingle and customers show off their purchase, but there are usually significantly higher costs with more staff onsite... but if you can pull it off without those expenses, then I'd say go for it... that was what our original business plan had designed.
You're right to keep it very simple for the customer, but I think printing options will be foreign to most and cause more issues than you hope to solve.