That's true, but it's easier to do while using them. You can "read" Spanish without knowing Spanish. You can't do the same with Japanese.

You can pronounce written Spanish words without knowing what they mean. However, I imagine that most people actually want to know what they are reading.

Also true, although you could get the pronounciation very wrong. It happens to be a few time with English. Regardless, being able to read it make it easier. For example, search for "industria" is easier than searching for "業界", especially for text on a picture. Google translate's OCR is not great, and reproducing the drawings to get a translation is painful and takes a lot of time.