Is "English Only" Unnecessary?

Linguistics professor and author John McWhorter believes that the English Only advocates are concerned about a nonproblem. An excerpt:

It is also easy to forget that America too has always been a linguistic cacophony. In the 1800s many big cities had several daily German newspapers. A preface to an 1834 book told us that for the man on the go, German would “greatly facilitate his intercourse with a very valuable part of our population.” One writer had it that in Lower Manhattan after dark “The US language is a hard find” — in the late 1800s.