A regional pronunciation that's ingrained in the culture is no more or less correct, particularly for a foreign word. And the Japanese pronunciation of western brand names is similarly incorrect (mostly due to the limitations of their language but the point stands).

The Western world encompasses many more languages than English. My mother language is Spanish and we pronounce most Japanese names correctly. It helps that both languages have the same 5 vowels and a similar set of consonants.

Japanese is not hard for English speakers. I bought two lots of minidiscs from Japan and was listening to them before recording over them and my wife was somewhat surprised at how singing Japanese does not sound all that foreign to her. Chinese, in the other hand, really does sound different, and personally I find the sounds of French much more difficult.

The problem are the vowels. Germanic languages are notorious for having a large number of vowels that may not even be consistent across dialects. Add the funky English spelling, and it is no wonder that English speakers will mangle Japanese names beyond recognition.

But yes, Japanese has pretty simple sounds and prosody and it is easy to pick up. I studied French for 5 years, and I could never get the pronunciation right. I know how words should sound, but my mouth just refuses to do it. I also studied one year of Chinese, and while I enjoyed it a lot, good god is the phonology difficult with all the weird consonant and the tones.

Going in the other direction, the official spelling of Pfizer in Korea is 화이자, which sounds a bit like why-jah. A game of telephone going through Japanese, which somehow stuck.