Chinese consonants are all not pure consonants as compare to English consonants. Chinese consonants are all embedded with a comfortable vowel to it. For example, the Chinese D are embedded with a vowel E, Chinese CH are embedded with a vowel I.
As a result, you will probably need a transitioning vowel when the consonants are combined with a vowel whose movement is easier to be comfused its embedded vowel. the transitioning vowel also functions are a quasi consonant. For example, u=w, i=y, v=yu.
English consonant, except l/m/n/r, are almost pure consonants. They don't have embedded vowels with them. So they can natually come togather with any vowel without bringing much confusion.
The level of tolerance on sound confusions are high in English than in Chinese. That sounds like Chinese have straighter, solider tongues. Japanese does not have middle transitioning vowels. So you can tell Japanese speaks less optimal English than Chinese. That's natural.
