Adults Who Love Toys? The Toy Industry Loves Them, Too (bloomberg.com)

Wondering if this is a sign of a certain type of social decline, but maybe I'm just a curmudgeon

I think you could point to any era where adults want to recapture things they enjoyed in their youth. There's a reason muscle cars from the 60s-70s go for so much money now - they were objects that teenagers lusted over in that time and now they're adults with the budget to buy it (or get it back).