Lol... you stay banned because your accounts were banned for cheating. They only unbanned people who were mistakenly banned or weren't aware they were breaking the ToS while using certain websites.
I used Pokefarmer and got banned. I appealed and got this in my inbox the other day: "We have restored access to your Pokémon GO account. Your may not have realized that an add-on app you were using was impacting our service. For this reason, we are unbanning your Pokémon GO account as a one-time courtesy."