I do not see how this is possible. The English alphabet allows a reader to memorize 26 characters and then be able to read the entire language. (although not perfectly because not everything is written phonetically) Memorizing 2,136 Joyo Kanji requires much more effort. Not to mention learning the varies combinations. Alphabet also has other advantages such as the ability to read root words; Ease of being able to look up a word in dictionary. etc.
From a 100% practical point of view, an alphabet is clearly a superior writing system.
English has no verb conjugations like the other European Indo-European languages. ( I might be wrong here but I am pretty sure about this)
Likewise it has no noun declinations.
Being able to conjugate verbs and decline nouns like a native German or Russian speaker is incredibly hard for a English speaker. A Chinese speaker with no shared indo-european grammar would find it even more difficult.
Amount of memorization required
Lack or root verbs or pronunciation ability
etc.
Yes it is possible to objectively rate the difficult of learning a language.
Also I am sure there is a Confucist or Daoist proverb about choosing ones battles wisely.
One of my friends attends USC and met with the Apple recruiter. They said they were only looking for students who could speak Mandarin, Cantonese and English fluently. With the recent increase in intl chinese students, a typical non-heritage or non-native-speaker just does not stand a chance in the job market.