[Nyororin]

English has no value for learning Japanese. Nothing in English helps you with the language, and you should be avoiding materials in another language when learning one to begin with.

Learning English in order to learn Japanese is so incredibly convoluted that I find myself having trouble even expressing how silly the concept is.
It is sort of like you having a broken leg and instead of going to the doctor and trying to start the healing process, you decide to wait until you are proficient at using a crutch to bother. It makes no sense in the long run.

I am a native English speaker and I found avoiding English and English language materials much more effective for learning Japanese. I was actually involved in a study following learners of Japanese as a second language. English language and English language materials did the complete opposite of help. There is a reason why immersion makes sense - isolation from another familiar language.

English may be a valuable world language, yes, but if you use that argument there is no reason to bother learning any language other than English. You start getting into "everyone should just learn English and communicate using it" territory.

Seriously though, not everyone is going to be in a life situation where speaking English will hold more value for them than Japanese (or any other lesser-by-your-opinion language).