The mass market doesn't buy, and doesn't want to buy, products based on what they might become months from now if these companies somehow dramatically improve the software. They buy products for what they are today, out of the box.
I would wager that, sometime between now and 30 June 2012, iCloud will offer a web interface just as good as if not better than MobileMe's (and quite possibly, under the hood, based on MobileMe's). They just haven't announced it yet, and if Apple hasn't announced it, they won't talk about it.
In short, there is no reason to assume that iCloud as it will exist 12 months from now will be limited to what was announced one week ago.