Unfortunately - it is the lowest common denominator stuff here. I had the pleasure of sitting through lots of meetings about this topic in a previous job.
The expert opinion from COI and the agency that do the web site is that people do not understand terms such as Black Watch, Fusiliers, London Scottish, PWRR, etc. ever mind that some of these units have been in existance for 100's of years!! Utter Bollocks
It is also to reflect the fact that cap badges, in the TA, do not exist in their own entities, but are now part of regional regiments - 51st Highland, London etc.
It sucks - and is why i no longer work where i once did