My DH bought a portable DVD player for the car and DD and I rarely use it. She can easily be entertained (or sleep) with other toys for up to 4 hours (with potty breaks). I think that adding a screen to a bouncy seat is lazy parenting. Pick up your child. Let the child crawl, roll over, and interact with his/her world.
DD is going to be tech savvy. Keeping her offline when she's 5 isn't going to hurt that. Honestly. She doesn't need a computer, a tablet, a laptop, an ipod. She knows how to work my phone just by watching me. Her dad and I have techie jobs and we just don't think a toddler needs a device. If you have to put a kid proof case on it...isn't that a clue that a kid might break it and maybe it's not entirely appropriate? I got really tired watching my SD break things when she was too young to treat them right. But it wasn't my money....
But that said, while you can argue about walking uphill both ways in the snow, there are a lot of products that make our lives easier, for good or ill (don't get me started on my college using the card catalog for scrap with a buggy computer system). Just because DD is unlikely to use a card catalog doesn't mean she won't know what a library is.
The end of your post though - I don't think that screens = violence. As a parent or guardian, your job is to watch what the kids read, listen to, watch on TV or at the theater as well as monitor screen time. When SS was younger, a friend brought over Grand Theft Auto...and it went on the box by the door and straight back to his house.
There are a TON of things on the market that are stupid, unnecessary and just plain wrong. And sadly a ton of people who will buy them. I feel sorry for the babies who get stuck in a chair with a screen instead of being held. Or stuck in a chair with no screen. I know that happens, too. Screens have their place, but IMO it shouldn't be in front of an infant. who barely knows he has feet.