Think of it this way.

In ANH we know that Red Leader's attempt to hit the exhaust port of the Death Star failed but the model makers still bothered to put an impact mark in even though the majority of people watching the film probably didn't notice it.

The same goes for adding a little visable chink in the exposed neck armour of the AT-AT.

The majority won't notice it, it might not be necessary in terms of what we know of the scene but it adds a little bit of in universe realism to what is happening.

That's why I'd be glad to see it if it can be done convincingly.