I'm sorry if I'm being mean, but what? You just put a list of reasons why you think people like pokemon.
Anyways, back on topic, a big reason is nostalgia. Now, I've only been playing pokemon since Gen 4, but that is because it gained so much steam. Great start means great profit. So many people loved Gen 1, this causes a huge rush in popularity. However, as years past, people will tend to leave. However, since it got that initial push a series needs, it was able to gain enough popularity through each generation to still be relevant.
It is also because it is a beloved genre by many and it is simple. Yeah sure, not everybody loves RPGs, but you have to admit they ARE pretty popular. What is not to love about adventuring, raising your own characters and shaping them how you want them to be. It is so simple yet it has so many layers for strategy. Unlike other genres, you really get to create and be the character instead of being in the shoes of another character like a soldier in an FPS. Sure, there is a certain main character and a certain plot, but your actions will play a big part due to customizability. (What I'm saying here is true for other genres but in an RPG, you really control the character with how you distribute stats, etc.)
Oh yeah, another reason why this is popular is because it is FREAKING POKEMON. What else is not to love about going around the region with your friends challenging others with the monsters you collect and train!? 721 FREAKING POKEMON. You get to go around on your journey, collect the ones you want, battle other stronger opponents and STRIVE TO BE THE BEST.
CUE MUSIC!
I WANNA BE THE VERY BEST LIKE NO ONE EVER WAS...
TO CATCH THEM IS MY REAL TEST,
TO TRAIN THEM IS MY CAUSE!
I WILL TRAVEL ACROSS THE LAND,
TRAINING FAR AND WIDE
THESE POKEMON, TO UNDERSTAND
THE POWER THATS INSIDE!!!
POKEMON