Rearview mirror adhesive, - use pad or just glue Options

[Sprout]

My rearview mirror fell off, so I bought a Permatex extreme strength liquid adhesive kit. The old mirror base still had some of the old foam pad on it, so I cleaned all that off, as well as the windshield. Before I put it on, I found an old thread on here where someone said to only use the adhesive pad similar to the original, and NOT glue the base directly to the windshield.

Does using the pad really matter that much? Have people glued directly to the glass and not had any problems?

Thanks