Actually it was because they decided to make it really small an they did cut back on funcionality. Here in Europe MiniSDs are also more expensive, harder to find and non standard (at least not as standard SDs).
I was waiting for the n810 and I had the money ready, but then I heard it was gonna use MiniSDs. It's not about the money, it's just that for me SD cards (and the price they cost, amount of memory available per Euro and compatibility with the cards I already have) are much more important that keyboard, GPS, transreflective screen and small size.
So yes, now Nokia has a smaller Internet Tablet. Great. I heard the next model is goint to be even smaller, as small as a matchbox. It won't have wifi, screen, speakers, bluetooth, memory, keys and a powerplug, though... It's the price for miniaturization...
I will keep using my n800.