If all the features described so far is kept, it would probably be a good idea to keep the possibility of mesh on the CPU/PSU outlet side as well since some people seen interested in flipping the case up side down.
This. When the case is horizontal, or indeed as you point out Urelure 'upside down', and you have either slow running fans or semi-fanless/fanless PSU or CPU cooling then dust/dirt could again get in. It'd be nice to have peace of mind that the case could be used indefinitely with future components in any orientation without fear of dust getting in through large, unfiltered vents.