The short answer, never going to happen again.
Here's why. Television cartoons were created as a product to sell first, and children's entertainment second. Most of the shows you posted are examples of this.
Most of these shows came with Toy lines, accessories, and and other merchandise that companies could shill out. To this day, that's still the main drive to sell a tv show.
And if the show can shill out merchandise using sub par animation, then that's the new standard studios are going to set themselves to. You can thank the fucking MLP fanbase for this.