All languages are filled with exceptions, and phonetics aren't that hard to grasp. Given the large amount of native material available and the fact that everyone is getting immersed in it starting an early age, as well as the fact that it is pushed on kids at the prime of their learning phase, it is considered extremely accessible. Roman alphabet, no special characters, very basic grammar barring the exceptions. Similarity with many European languages.
Also, thanks to the whole world speaking it to an extent simplification is in the making with all but the most elitist embracing it. Grammar mistakes, spelling mistakes, pronunciation mistakes, etc are slowly making their way into the language and changing it. This happens with all languages, don't get me wrong, but when you have half the world working on it it's a much quicker process.
(well, that and American spelling helps with things...)
Srsly though, English isn't a hard language. It doesn't have the phonetic nightmare that are the ma ma ma ma ma ma mas, the unusual alphabets, the gazillion verb tenses, no accents, conjugation is generally easy, irregularities are slowly becoming flattened.
Extremely basic mistakes such as inability to tell logicalyl written words apart just because they are homophones are ridiculous, and compared to other languages you have it easy (Japanese, anyone?

). And yet even those are slowly becoming acceptable, thus making the language even easier.
P.S. It's not that it has one of the largest vocabularies on the planet, it's just that it is so easy people actually get to learn all them fancy words because they have so much free time with it.
Edited: 2012-01-18, 6:45 am