Mostly because it's rare to see identifiers with whitespace allowed after all. So this has to fulfill some specific needs.

The main use case here seems like self-describing properties that will be hardly referenced elsewhere. In principle this doesn't really need any new syntax, as you can put the description into the attribute (`[<Property>]` here) and the name itself can remain arbitrary or even be made anonymous. But we've got textual identifiers instead. So I guess that some code does refer to those textual identifiers, and if that's the case, being able to ignore invisible differences when comparing textual identifiers looks like a good idea as well.