Not just in AIPs, but it's ICAO standard phraseology.
"Instructions transmitted are to be complied with and,
in most cases, should be read back to reduce the chance of any ambiguity or misunderstanding, e.g. ‘G-ABCD, taxi to the apron via taxiway Charlie’. Chapter 2 specifies those instructions that are to be read back in full.
However, if the instruction is short, clear and unambiguous, acknowledgment of the instruction using
standard phraseology such as
‘Roger’ (I have received all your last transmission) or
‘Wilco’ (I understand your message and will comply with it)
is preferred for the sake of brevity in the use of radiotelephony transmission time." - UK Radiotelephony Manual CAP 413
https://publicapps.caa.co.uk/docs/33/CAP413v21_6.pdf
http://www.skybrary.aero/bookshelf/books/115.pdf
https://contentzone.eurocontrol.int/...y/Default.aspx
So yes, "Roger" has a place in RT. As long as mandatory items are read back, it is not misused. ("Charlie, Charlie" however,... that's just nonsense, unless you sail a ship.)
Don't tell me that when ATC tells you: "Traffic, 10 o'clock, passing left to right, climbing to FL360, 1000 feet below you, Airbus 320", you read back the entire message?