The thing is, the actual format was set out in a TS document and possibly a S too. ATC would not have had access to the TS and maybe not even the S doc. The safest way therefore was a verbatim repeat.
... Apart from one sgt ATCO in Local who was genetically incapable of reading the text of the message as written on the perspex card by the ATCA [the ATCA just had to fill in the gaps, the rest of the message was SOP and pre-printed]. Regardless of how often he was told, he still insisted on putting his own style on the RT broadcast. He also held the World Record for keeping the traffic lights on the A17 and the thresholds on red when there was no need. To55er!