[jcranmer]

Actually, it's probably a simpler reason than that. The Japanese language is largely a CV syllable string (consisting of a consonant and vowels); consonant clusters do not exist, and the only final consonant permitted is 'n'. English, by contrast, is a much more phonotactically complex language--consonants can pretty freely appear both before and after vowels in a syllable, and English also has several consonant clusters. Imagine trying to pronounce the word "strengths" if your native language lacks consonant clusters--it's like an English person trying to pronounce the Czech phrase "Strč prst skrz krk". On top of that, Japan is not great at English proficiency (it's definitely weaker than any other rich country, see https://www.ef.com/wwen/epi/).

It's not really that the written language makes the names hard for them to pronounce, it's that the spoken language doesn't make it easy, and there's probably not enough care to try to pronounce them. Where the written language does make it hard, it's usually when people try to localize Japanese media into foreign languages, and the intended references in names are lost because of the mangling process of transcription into katakana.

[hunter2_]

As an English speaker who has traveled to Japan without learning much of the Japanese language, I agree generally but I also noticed that there are some cases where a vowel is written but not pronounced. For example, "gosaimasu" is mostly pronounced without the "u" (creating a counterpoint against final consonant other than "n" being forbidden) and "gozaimashita" is mostly pronounced without the second "i" (creating a counterpoint against consonant clusters such as "sht" being forbidden). It gives me the impression that these rules exist more in written Japanese than spoken Japanese, at which point it becomes less clear why adding a vowel to the end of foreign/imported words is so common. Maybe it's just my English perception that the sounds /s/ and /sh/ consist of pronouncing only a consonant, when in reality the fact that those sounds have duration (not just a moment) actually means it's more of a vowel even when totally unvoiced!

[hunter2_]

As I think on this further, even these voiceless /s/ and /sh/ sounds involve putting the lips into either an /u/ or an /i/ shape based on the following vowel even if that is also voiceless, creating that which is not a syllable in English, but perhaps is for this purpose in Japanese. The C-V cadence and final vowel (given lack of final -n) rules are satisfied...