The glass and the display panel are actually completely glued to each other, eliminating air gap so you touch what you see, reduces reflection and scattering, also it makes the display stronger and less likely to break.
If it does break however, you end up with a glued mess that needs professional skills and tools to separate and reassemble without ruining it for good.[br]
If you don’t clean up the residual glue and use a laminating machine to glue everything back together, the screen will look like someone just puked on it.