Gateway was probably hoping everyone would just believe their "memory corruptions due to flawed copying" line and in turn buy their cart just to stay safe.OK, shills aside, let's play pretend for the sake of audience.
"I don't see how this would discourage new customers, either."
New customers come only from the pool of 4.x FW users, and GW just killed a bunch of 4.x consoles which are getting sold out already. Now think about where the missing users to be converted into new customers are going to appear from.
(cost of a GW cart vs another compatible 3DS)
Why else would they set it to brick at random as opposed to 100% of the time?
They didn't want to drain the pool. They just wanted to make a splash.