The last thing I want to see when I pop open an engine bay is a giant sheet of high-temperature plastic. The guy who convinced the whole auto industry this was a good idea should be shot (not to death. You know, like, with a squirt gun or something), because the beautiful machines providing the motivation for our vehicles deserve more than an ugly hat
Our engine bays are getting uglier. Part of the reason for that is because no one cares about how an engine should look when the flow simulation program testing the prototype intake says you can be .05% more efficient by bending a pipe this or that way. That's fine. Pretty engines are more of a perk than anything else. But not being able to give us an awesome top half is no reason to just slap a sheet of corporate logo'd plastic on the thing and call it a day.
If you're going to do it, you can at least be tasteful. You can at least put some effort into it. How about a pair of covers topping a great looking intake manifold? Or even one that improves the look of the engine? It's worse than nothing + great looking engine bits, but it's still better than a flat sheet of cut-to-fit sterilite
The best engine bays don't need no damn plastic engine cover. To prove it, here's some engine porn.