For me, the main reason for mobile games are popular is precisely because they can be played anywhere. It may seem like a simple concept, but in the rhythm of life that we live today, being able to take the games to anywhere is always an incredible differential.
I guess you're right. The who point of mobile gaming is to be accessed generally anywhere at anytime. Also, I think we've entered a freemium era of mobile gameplay that is being taken advantage of. Personally, however, I do feel overall quality mobile gameplay could be much better.
I think because a lot of mobile games are easy to download and free. Also, you can easily access it on your mobile where you can play anytime and any where.
Mobile games have low barrier for the entry. And also they can be free or say freemium. And they survive on ads. So not bad idea to play them instead of the paid games.
They are popular because you don't need a desktop or laptop to play them. You can play them on the phone depending on which version of phone you have. I think they are also popular because you can play them anywhere anytime. They are free and you don't need to subscribe to play them.