TV audience engagement currently requires (positively or negatively) engaging content. That's why you see people using sites & social media to engage around television shows.
Manufacturers & broadcast companies don't HAVE to cater to their users' engagement desires, but I don't think there's much to debate on the value of doing so. Interacting well with your customers and building a strong community around your brand are known ways to develop profit centers.
If TV isn't broke, why fix it? Because the status quo is ok as your business's starting point, but shouldn't be the end goal.