Plywood is fine for making a bass, as are many other materials. Cost, looks and tone are all valid reasons to use specific materials.
My take on this. Unless you are in the business of listening for tone in materials you're not going to be very good at identifying the small differences. Unlike tea, coffee, perfume, whiskey blenders and some makers of musical instruments our senses will not be developed enough to be able to comment whether this material or that material makes a difference or not.
We don't know what we don't know. We can say what our preferences are, but I just don't get why people think they know all the answers and reasons, when they clearly don't.