I had a similar discussion with my other half not so long ago. If your child scores over 121 brilliant - what more do you need to know? If the score is below say 115 - it wasn't meant to be. Between say 115 and 121 are the ones that need to know their precise score in order to make an informed judgement on whether an appeal should be lodged. (In my opinion
I imagine it is quicker and cheaper to generate generic letters with a numerical score on than splitting the letters so some have grammar, others have upper and the middle ground have appeal or actual numbers.
In the olden days of the 12+ we (our parents) weren't told our scores - we (they) just got a slip of paper with the name of a school on it - either a grammar or seconary modern and that was that.