"The main goal of optical bonding is to improve the display performance under outdoor environments. This method eliminates the air gap between the cover glass and the display"
GS4, iPhone5, Nexus 4, Nexus 5, HTC One (Horrible offender here).
If you get an 8/10 on iFixit, you have about the most perfect score possible with top of the line phones.
if you do decent product design instead of copying every bad decision apple made, you'd have the glass framed. It would have no discernible air gap. all the things you said would be just as fine. and it could be replaced by removing the frame, probably with screws.
but no, let's use corning glass (with lots of impurities so it is crack prone but hard to scratch... the perfect glass to be framed) and use it on the whole front of the device so it is guaranteed that it will break if the device falls.
sometimes i really wish apple had had it's way on the illegals claims about owning design elements. we'd at least be safe from their bad choices.
Just about the only downside to fusing the display is repairability.
and yes i know corning glass decision is only because it does not scratch.
my main point thought is about extending a fragile glass like corning to the corners.