You're being dramatic. This block doesn't replace building with Lego. Nobody is going to buy the block as a replacement for making blocky dinosaurs and racecars. We know this because Lego already shipped Technic and Mindstorm products that never broke the core value proposition.
Having grown up with Duplo, Lego and Mindstorm, I think this brick is awesome. I can't wait to see what Minecraft Redstone engineers build in real-life.
I understand the grandparents viewpoint. Why add constraints to an open ended toy? On the other hand, you could argue that the instructions and included pieces are constraints. Should Lego just sell random grab bags of pieces?
If they're going to call it the "most significant evolution’ in 50 years" I'll be just as dramatic about how much this feels like a gimmick and a brand withdrawl, not a deposit.