The main reason is "because Google is behind it so it actually has a chance to become a thing". Otherwise, they're designed to be unlikely to generate offensiv

The main reason is "because Google is behind it so it actually has a chance to become a thing". Otherwise, they're designed to be unlikely to generate offensive terms, and the + makes it feasible to use a shortened code together with a given or implied city name. Most of the improvements in this space are small details, because turning coordinates into a string is a really simple problem (which also attracts a lot of "let's reinvent this"...)