While I was working on #8247, I was testing a lot of blocks, including some that have Block entities that are currently not allowed as facades, and didn't notice any problematic issue with them.
In fact, except for the ME Cable and / or Bus (which crashes trying to render the facade of a ME Cable and / or Bus...), all blocks I put into facades behaved fine, falling in anyone of the following categories:

• rendered fine, about what one would expect from the block (e.g. ME Drive)
• rendered, but with lots of z-fighting (but also expectable from a 3D model which got flattened) (e.g. wireless access point)
• didn't render at all

Currently, in order to whitelist a BE one has to both:

1. enable the config setting for BEs
2. put the block in the tag that allows it as a facade

I'd like to change it, so

• 1. all BEs that are in the tag will be allowed in facades, regardless of the config setting.
• 2. make it so the config setting allows all BE as facades, as long as they are still full cubes

I'd be fine with just 1. and not 2., but I'd really like Me controller facades to be accessible by default (because that means one can effectively get decorative ME controllers via facades)