There's an app store and browser add ons work well.
The hardest thing for a casual user to learn would be "sudo apt-get install" and then guessing what the package name is that they might want to download, like vlcplayer or java
Everything you said in this sentence is a deal breaker for a casual user, and a terrible user experience in general.
Linux takes time. Life is finicky. But for the average Thai person or Vietnamese living on $300 a month, a $100 investment is more palatable than $600