I'm not sure what their keyboards have to do with it. If you were a native Arabic speaker, wouldn't you want to to be able to see domain names in Arabic that are easy for you to read and type? If you're a company operating in an Arabic market and you want to put your domain name on the posters you're designing to display at bus stops, you probably would prefer an Arabic domain name so that your primarily Arabic-speaking audience are more likely to remember it instead of dealing with an alphabet which belongs to a completely different language they may not speak at all (or not very well).

I know English is increasingly pervasive, but there are still billions of people who don't speak it at all or speak it only very poorly (and it's not exactly very easy to learn). The internet is a global network, and so should allow people to communicate easily in their own languages. This current pain with IDN is just a legacy of the internet's origins in America and Western Europe.

Heck, the example in the article are just using one letter found in German. You don't need to go very far from English to find these problems.