Concatenation # operator for identifiers and literals

As we all know, the # operator is able to concatenate some identifier-like pieces into a single one:

Code:

match ,
{
  abc # def equ display 'OK'
  abcdef
}

If also works with string literals:

Code:

match ,
{
  display 'abc' # 'def'
}

Still it doesn’t work for identifier and literal:

Code:

match ,
{
  abc # 'def' equ display 'OK'
  abc'def'
}

while

Code:

match ,
{
  abc'def' equ display 'OK'
  abc'def'
}

works as expected.

I understand the possible ambiguity of whether the result of such concatenation should be a string or an identifier but I also feel being able to concatenate a string literal to an identifier (having a new identifier as a result) would open a lot of possibilities for writing macros that require bookkeeping based on (macro-)user-provided string literals. (I remember it has recently been the case for multisection macros.)

Any reasons why defining the # operator behaviour for non-equal “types” might be impossible / a bad idea?