I use mesh bags because I don't care about the dry factor in my Ortliebs and the same ones can be reused for decades. I got tired of throwing out other bags at the end of a tour. I also use the same bags when traveling to keep my stuff organized. Of my 4 Ortliebs I only use this system in my 1 clothes pannier. My other panniers don't need as much organization.

I tend to pack light so I don't run out of space in my bike bags and actually prefer them to be "full" with my expanded gear.