I guess the difference is that in Japan, all phones have had push email accounts for years. Instead of being @mobileme or @yahoo.com they are @carrier.jp and are created when you purchase your phone.
Instead of being charged per message, you are charged per packet. So if you like to write very long winded messages, they will end up costing you (marginally) more.
In Japan, the push problem is solved without MMS. It just takes all the carriers to cooperate with each other for the benefit of everyone. And as a Tokyoite, I thank them.