> This could explain the result for Hindi - it is a standard language that 'averages' a large number of other Indian languages.
I think this is a little misleading; a lot of Indian languages come from a completely different language family to Hindi (Hindi is Indo-European, but a lot of Indian languages are Dravidian, e.g. Tamil and Urdu), though I'm not qualified to speak about this.
Incidentally, your comment led me to this http://en.wikipedia.org/wiki/Hindi–Urdu_controversy which you may find interesting.
English is thus - for all intends and purposes - not weird.
A more interesting approach would be to take larger languages, like English, Mandarin, Spanish, etc. and value their features higher than languages spoken by tribes or very few people, and thus you could determine a more accurate 'weirdness' index out of that.
http://en.wikipedia.org/wiki/List_of_linguistic_example_sent...
1. There is not a universal definition of what defines a language and what is simply a dialect or a regional variation; this applies especially on large continents where there can be greater variation in language features between geographically remote locations, but no clean boundary at which you can say people speak one or the other language.
2. Languages evolve, diverge and sometimes borrow, and so a group of related languages can share the same potentially idiosyncratic feature because of common evolutionary roots rather than because the feature makes sense. This could explain the result for Hindi - it is a standard language that 'averages' a large number of other Indian languages.