Rats make great pets- I kept pet rats long before I ever "accidentally" got into snakes, & they're cute, intelligent, trainable, & even affectionate animals. I agree that it's sad that so many are treated poorly because they're "just feeders" -but truthfully the same is often true for the animals consumed by humans.
Those rodents labeled as "fancy" are also usually more genetically diverse- they may have various coat colors & markings, or they may have been bred for other appearance variations too (such as "dumbo" ears, wavy-coated "rex", etc). Some of these variations actually ARE harder to breed for- I can vouch for that being the case with fancy coated mice such as "silky" (fine long coats) & "satins" (fine, short shiny coats)- because I used to produce them when I sold to pet stores, so that does justify the higher price & the "fancy" label, but otherwise most rats & mice cost the same to raise- & ALL deserve good care & humane treatment regardless. Unhealthy rodents aren't good for your pet snakes either. I find it every bit as disturbing as you do that so many animals raised as "feeders" are mistreated, & I'm glad you cared enough to ask & choose sources carefully.