To be honest there isn't really a definition for things like "Pokemon Master" or "Dragon Master". Kinda like Luffy + Pirate King definition I guess. For Ash, being a Pokemon Master probably just means he gets to travel around the world with Pikachu & his other Pokemon and experience new battles & events etc. Remember he saw Ho-Oh on the first episode? Ash's eternal happiness is not to win, but to be with his Pokemon forever.
Ash just does what he wants to do, and you're being awfully judgemental about his abilities. Considering that he saved the Pokemon world countless number of times, it really makes you wonder why people are so condescending about Ash.
Form an anime script point of view, it would be awfully boring if Ash actually won something too major. The entire Pokemon anime hinges on the journey/ character development aspect, and yes they could get a new main character - which would probably be better - but if they were going to keep writing Ash as the main character, then his character growth wouldn't be able to be expanded upon if he just went and got a championship somewhere and became champion of that region.