By a lucky coincidence due to factors above, English, the Universal language is one of the simplest and easiest natural languages in the world. The only other simple and easy languages are constructed ones.
Of course the concept of easiness is relative, and it depends on which language you know already. However the concept of simplicity is undeniable: English in an easy language to learn understand and speak. A complex language such as Hungarian would be a very unlikely candidate for a universal language.
First of all, English Language uses Latin alphabet, the most universal, simple and short one (only the Greek alphabet is shorter and simpler). In addition, in English, the Latin Alphabet presents its most "clean" form as a true alphabet with only 26 basic letters and no diacritics;
Verb conjugation is very simple and easy. Even for irregular verbs, there is almost no variation in person (except 3rd singular in present tense).