Steven Gerrard's side claimed an away Old Firm victory in the Scottish Premiership for the first time in 10 attempts as Nikola Katic's winner saw it beat Celtic 2-1.
Yet Rangers, who moved to within two points of their rival at the top of the table, with a game in hand, ended the match unhappy with the officials.
Gerrard goes nuts after Rangers win
Odsonne Edouard's initial equaliser for Celtic appeared to strike his arm, while Morelos was sent off late on - his seventh Rangers dismissal - receiving his second booking for diving as his miserable goalless Old Firm record continued.
The absence of VAR - the system much-maligned in England's Premier League on the same day - in Scottish football is of frustration to Rangers, as Robertson explained.
"This is not a criticism of referees because they often have to perform under very difficult conditions and in a highly emotive environment, as do our players and coaches," Robertson said.
"The speed at which the modern game is played also means it is extremely difficult to make split-second calls with the degree of certainty required.
"We believe the introduction of VAR would help referees enormously and reduce the number of wrong decisions which sometimes have a dramatic effect on the outcome of matches.
"In recent weeks, Rangers has suffered from errors of judgement but it is our strong view that VAR would be to the benefit of everyone and in particular the referees themselves."
Rangers' statement highlighted three "glaring errors", referring to Edouard's goal, the non-award of a penalty for Morelos against Aberdeen, along with Celtic's offside winner in the Scottish League Cup final.
The release went on to defend Morelos, who has been criticised for an apparent throat-cutting gesture following his red card at Celtic Park.
The club said: "There can be little doubt Alfredo is singled out for special attention, on and off the field of play.
"Indeed, some of the things said and written about him leave a lot to be desired and do nothing to suggest Scottish football is the most welcoming of environments.
"Even Alfredo's gesture as he left the pitch is now being portrayed in some quarters as something sinister when, in fact, it is a gesture used commonly throughout South America to indicate quite simply that something – in this case, the match – is finished."