Default Currency Journal Entry marked as "Multi Currency"

Continuing the discussion from Journal Entry - Multi Currency by default:

Not having to think about whether an accounting transaction (Journal Entry in my example here) it “Multi Currency” or not would streamline a very common procedure in our daily accounting routines quite a bit. Many transactions are Multi Currency, so I want to change the Default behavior of the Journal Entry to haveing the Multi Currency checkbox to be ticked by default.

Ideally I would just run any Journal Entry as Multi Currency (even the ones that are entirely in default currency)

I know how to set this up and first test seem that a default-currency Journal entry does not suffer in any way when it is marked a “Multi Currency”.

Can anybody advise whether there potentially may be some sort of bad behavior when doing this?

The mere fact that a “Multi Currency” switch exists and it is unchecked by default makes me wonder.