This reminds me of the same thing that happened with feed brands. A few decades ago, kibble quality went up, prices started to go up. New brands, new varieties of older brands appeared. These were marketed and people bought them and often liked them. Then ingredients were altered to be cheaper while feed prices continued to increase and then bag sizes decreased. I hope the same trend is not occurring with flea products!
I do think the parasites develop some resistance to the products over time. I don't know what the solution to that is, beyond rotating products. But since Frontline has a broad sales base of people buying it, and a market at vet clinics, I doubt they will improve their formula or their policies.
I think the premium flea treatments are overpriced. It is worth the cost to me if they work. I depended on Frontline(plus) to work. It did years ago then it stopped working. I would rather my dollars go to support a smaller, cheaper, more readily available brand IF it continues to work for me. If not, I will get what does. My clinic doesn't even carry Advantage, although they offered to order it for me; I could probably order it myself cheaper but if I have to order it and wait on it in the middle of flea season I don't like that either.