How to View of commerce products with image from product_variation
Here's how I did mine : 


View of products
Add relationsip: variation image
Add that relation in the fields displayed (You'll now get all the images for the product
Add a field Product variation delta
Add a filter with the delta which equals to 0 (which will show the image of the first variation). 


It's not perfect as if the first variation as no images, it think it won't show up... But it should fits quite some cases.