Multitasking and Flash are software issues so they don't require redesign (I don't see Flash coming to iPad though).
As for the rest, particularly SD/USB and camera, it's interesting how folks are bitching about missing hardware features but quickly gloss on the fact that iPad starts at $499. Low price is one of the strongest features of iPad, a feature that will cause many to buy despite its limitations. These missing components may not cost all that much individually, but they add up. Apple clearly tried to make iPad as cheap as possible, without compromising on components it feels are important (e.g., screen quality).
I think choosing 4x3 screen demonstrates this. 9.7" 1024x768 SIP LCD with LED backlight probably struck best bang for the buck, while providing top-notch image quality in portable computing device category.