Using Keyboard Covers on MacBook

Do not use a keyboard cover.

Using a camera cover, palm rest, or keyboard cover on a Mac notebook - Apple Support

And, a keyboard cover will interfere with heat dissipation.

The MBA also "breathes" through the keyboard. One of the reasons it can have a fanless design is that air and heat can flow up and out of the machine through the keyboard. Something to consider.

Other's mentioned that air flow is reduced leading to increased heat.

The other negative is that it increases the thickness from the keyboard and can butt up against the screen and damage it.

The only advantage may be prohibiting liquid damage if you spill coffee, water, etc. on the computer.

Debris can usually be shaken out.

Yes, this factor outweighs the any potential benefit of the cover.

I and my fam have used many MacBooks over the years. None had covers. All lasted a minimum of ten years without keyboard, trackpad or screen problems. Just take care of the computer.

statician wrote:

Gotcha. So you'd say that this factor outweighs the cover's potential benefit of possibly preventing dust/debris build-up?

Just don't eat raspberries while using the computer on your lap and then fail to check that you hadn't dropped any before closing. ;-)

statician wrote:

You came just in time, I was smashing a handful of raspberries when I stumbled on your reply.

I actually dropped a couple on the MBA but up near the hinge, didn't see and closed it. Not my best moment but the MBA did survive.