Why isn't there more research in progress on how to wake up people from cryonics? Or, rather, why aren't more people sticking hamsters and dogs under liquid nitrogen*, then trying to revive them and bring them back to "full life", and seeing if dear ole Spot remembers all the tricks we taught him?

Because anything bigger than a cubic centimeter or two that you try to vitrify always comes out of vitrification full of massive cuts and chemical toxicity and ice crystals and leaky membranes to the point that calling it temporarily 'alive' is a stretch. This is not a problem with the revival process, but with the preservation process. Even freezing samples of cultured cells has a mortality rate.