It isn't wrong at all if you like Nintendo, everypony has their own opinions, I think that you should just hold onto your opinions and don't let others influence you too much. But in my honest opinion, I think that your brother is right all the way, except for the platformer part, platformers are still fun. However, I believe that Nintendo will eventually die out one day or another. Their 3DS only was a moderate success and their Wii U kind of like a dead pony walking. However, it doesn't mean their games are bad.