So is vinyl by that line of reasoning. The difference here is that plexiglas is thick and rigid (usually at least 1/16" thick) while the Lexan used for original CPO's is not.
Are we talking about the same Lexan here? As far as I know, Lexan is polycarbonate. It's what aircraft canopies are made of. It's what safety glasses are made of. It's what CDs and DVDs are made of. It's a hard, stiff material.
What do you think is on top of those metal control panels? Or on top of the wood control panels for that matter?
Either paint or vinyl stickers, I always assumed.
As a purely practical matter. . . .
If you only put something soft (like vinyl) on the top of your control panel, then you have to make the panel reasonably smooth. If there are recesses, then you have to cover them with something stiff. Having recessed components and covering with with something soft -- anything soft -- wasn't done in the old days for the same reason we don't do it today: because it doesn't work.
If you want to hide screws, bolts, dust washers, things like that. . . Then you practically need something stiff to cover them up. That could be acrylic, it could be metal, it could be something else. I'm not picky, but I'm just saying that's how it has to be arranged.