Shahmir, to me your first example is exactly a counter-argument. It's so easy to learn long words, beause they are different, it's so difficult - sheer horror - to learn short words. They are so similar one to another.
Is it cheng? or chang? or chen? or chuan? or zheng? or jian? or zhen? or sheng? or quan? or chuang? or ruen? or whatever. Oh, it's chuan, indeed, but not chuan2, only chuan4, can't you see the difference?????!!!!!
That's a horror, pure and simple. It seems so simple when you see them new words, but when it comes to say them from your memory you are never, never ever sure.
With long words you have plenty of possibilities, with short words there is so little choise of forms for so many meanings.
With long words even if you mispronounce 30 percent of a word in the middle or in the beginning or in the end, there is a hoygh lavel of prebability you ill be wonderstout enuhow, with short words there is no chance, unless the topic is obvious before you even say a word (then, why bother saying a word, indeed?).