Nooooooo!!!!!!! Please, no.

Since screaming NO like I'm being mauled by a bear probably isn't very helpful, I'll elaborate. 

iStock never sold sizes for vectors, and they were (probably still are) one of the best earners for vector contributors. I regularly had the same number of sales on IS as I did at DT, but I would make about 3 times more (even at 20% royalty) on IS because DT has subs and sells smaller sizes. If iStock would have paid me 50% like DT did at one time, they would have easily equaled the earnings of all the other agencies combined while selling a much smaller amount.  I just think selling smaller sizes vastly undercuts earnings.

From a buyers perspective as well, I regularly would buy the smallest size I need when purchasing images for clients. If all they offered was the largest size, then I would buy that for my client instead. So, contributors lost out on the price difference because there was one.

Yes, you could argue that you might miss out on sales for more budget conscious clients, but I think they don't necessarily help your earnings as much as they hurt them. In the end, if you offer someone the option to save money, they'll take it. Even if they don't care or it doesn't matter to them.

Thanks John, and yeah the optional idea is very good, you can see just by cthoman's posts and mine that we have different views on the subject.

It also means some of us can try it out first to see if it generates more sales without affecting our vector sales. I'm presuming we will be able to disable the feature once we have enabled it.