Google's webstore for extensions charges a one-time fee of $5 to mitigate the abuse problem. I think it's a reasonable compromise. Apple's $100 per year is also keeping my hobby extensions off Safari as well.
Not sure what you mean about poor design or maintenance. The lower barrier to entry means there are many more options and often unmaintained extensions get forked. (If their license is permissive, which is more often the case when the creator doesn't have to pay $100 per year.)