It's a matter of balancing the amount of support calls with the amount of 'plug and play' users and the rest of the 'security oriented' users.

I like when they make security simple, but some people get flustered by the extra work setting up a device ..
It's a matter of user ability that determines where the right 'break even' point is for developers.

Most wireless routers DO make encryption an easy feature to enable, but if forced on the user it may result in a lot of support calls. Those users concerned enough with the security issue usually find an easy way to accomplish the goal. Those who are clueless on the other hand ...

I do not work here, but the benefits are still awesome
Make your sound your own!