I think the reason many of people have stereotype of PRC is because the beijing accent sounds very stupid and sohai, unlike southern accent which is warm and friendly

Contrary to popular belief Modern Standard Mandarin is not the same as Beijing accent of mandarin. Beijing accent is a very different and non standard accent.

As capital of China the government should eliminate regional accent in it and promote Modern Standard Mandarin, remove erhua and beijing slangs, and use the absolute standard Mandarin.

This will entrench the status of Modern Standard Mandarin as the prestige and standard version of Mandarin, as well as remove stereotypes of PRC caused by the stupid sounding accent