Personally, I wouldn't have a problem with the mini-USB connector - it's not like anyone cared with the EFA-Linker for GBA. As for writing speeds, it's just the fact that everyone has been spoiled with fast removable memory. Ditto on the size. Thanks to removable media, you guys have been spoiled for choice with regards to size - 512MB can hold plenty of roms (I can load on around 10 on my miniSD). I find the less roms I have on my card, the more likely I am to actually play right through the ones I do have - there is definitely no need for me to have 50 or so games on a single device.
But all this is almost irrelevant if you just view it as technological progress (if the claims are in fact truthful). Unpatched roms on a perfectly sized DS slot cart, not requiring any sort of passthrough?
If you want to bitch and whine, stick with what you have.