What is it that makes you desire to return to the new games each time one is released to play it? Is it the prospect of new story? New characters? New Pokemon? New areas? New online battles and functions? Or just returning to something familiar?
Personally, I think I find that I get excited each time a new main Pokemon game is announced because I am looking forward to embarking on a new adventure again, and seeing anything that is new within the world there, as well as experiencing a familiar story, with familiar gameplay. It's within a certain comfort zone so I'm aware of certain things contained within the game, but there's a lot of fresh things too - I particularly like seeing what the new gyms will bring.
Personally, I think I find that I get excited each time a new main Pokemon game is announced because I am looking forward to embarking on a new adventure again, and seeing anything that is new within the world there, as well as experiencing a familiar story, with familiar gameplay. It's within a certain comfort zone so I'm aware of certain things contained within the game, but there's a lot of fresh things too - I particularly like seeing what the new gyms will bring.