Had the opportunity to see a 1903 Buick overhead valve engine run and it didn't even have a valve cover. The reason it didn't, you had to stop every hour and with an accessory oil can, had to oil all the valve train parts. Had, the opportunity to do this, that was fun.
Since then seen thousands of engines without any cover whatsoever, wires and sensors, fuel lines, etc.m going all over the place, tractor engines are completely exposed to the environment.
Only thing I can say about the Cruze camshaft cover, its purely decorative, not even a dust or a water shield, completely opened on all four sides. It is pretty, but can't see where it serves any other function. Ours was touching the front of the camshaft cover with an annoying rattle, put a piece of weather strip under it. And you never want to pull this cover off when it is cold. That plastic becomes very brittle, should be a warning sign on it.
Can still get dust and debris in the spark plug wells, should blow those out with an air compressor first, so whatever is in there doesn't drop into the combustion chamber. This has not changed for years.
From a practical stand point, both the engine camshaft cover and this thing that covers the engine camshaft cover should have been made of cast aluminum, and that top cover should be bolted down. This would entirely shield the entire ignition system to shield from EMI, electro-magnetic interference. We had to do the same thing with alternators, before just a front and rear cover with the stator exposed. Also made assembly a lot easier.
Essentially you have 40,000 volts interfering with all that high impedance 5 volt logic running all over the place. But plastic is a heck of a lot cheaper. Was really a problem with spark plug wires running all over the place. If a guy installed an after market set with wires too long would run into all kinds of interference and wonder why he was getting codes.
Yeah, that thingy that barely covers the engine camshaft cover is purely decorative.
Even I could afford this. So its called an engine appearance cover. Should be able to pick one up from your friendly Chevy dealer for 11 bucks. Doing a net search, shipping is the major cost for this part. Ha, print this out and show him the price.