My first thought in response to this is the vendor's support costs - wouldn't shipping more reliable images bring down those costs signficantly? Or is it just that the extra revenue opportunities gained by adding $WHIZBANG_FEATURE_DU_JOUR outweigh those potential support savings?
When presented with an either-or decision like "Doing <X> will make $M but doing <NOT-X> will save $S" then in most public companies $S would have to be more than $M x 2 before <X> will stop happening. In this case $S is not even a notable fraction of $M so it's not even worth discussing. Somebody here said router design was a political process. I disagree. But networks are complex systems owing their existence (and their nature) to an ever shifting matrix of politics, economics, and physics. And, Heraclitus' maxim is very much appropos here. The target for a router designer is moving.