you pretty much answered your own question when you wrote about nintendos answer to why you cant make new friends via wifi
thats why there are forums like wiichat where you can volunterally add whomever you wish. its at your own discression. god forbid like you said you get some person whos in their 50s and is a future "dateline" perp.
you have the option of adding kids in your own age group or you may add everyone and anything under the sun
until wii online comes out, there truely is no other reason to have wifi. so just give it time. like all new systems on the market, it needs testing