Originally Posted by winstein
As much as it will be a thrilling thought for Ash to age so that there is some semblance of progress we see in him, I think it's probably for the best that he stays at 10, because if the purpose of the character is to journey through the different places and be entertaining to children at the same time, that's the best way to go. He also tends to make repeated mistakes, which some fans over at Bulbagarden complained, so if he's still at 10, this would be justified a bit.
By the way, at the age of 10, his understanding of romance is limited, like many children like me when I was 10. Besides, Takeshi Shudo (late writer of the anime) even said that Pokemon and romance doesn't blend well, so making Ash a romantic fella may not be the best idea to do in the anime. Thus, another reason he's best stayed at 10.
Thanks for reading.
Couldn't agree more with this. I think another point could very well be that a lot of other anime's, the main characters have grown up (I'm looking at you naruto!) And people expect the same to happen to pokemon. Still, there's no pleasing everyone.