But the former Lions coach was quick to highlight the fact that both Academy players Crombie (hooker) and McKenzie (back row) had merited their call-ups after impressing while training with the squad.
Robinson said: "Both of these boys deserve to be in contention after training well with Edinburgh throughout the season.
"We are always looking to promote young Scottish talent and both Sean and Fraser are good prospects."
Edinburgh are without Allan Jacobsen (groin), Ross Ford (ankle), Roland Reid (hamstring) and Alan MacDonald (fractured cheekbone) who are all ruled out through injury.
Meanwhile Greig Laidlaw, Ally Warnock and Scott Newlands are away on international duty with Scotland's 7's squad in Hong Kong.
As a result, Robinson admits he has been forced to reshuffle the squad ahead of the all-important visit of Cardiff Blues.
While coaching on the Lions Tour to New Zealand in 2005, Robinson worked with Gareth Thomas, Tom Shanklin and Martyn Williams and he acknowledges Friday's fixture will be a difficult obstacle to overcome.
He said: "I was fortunate enough to have worked with those guys with the Lions and I know how committed and talented they all are as professionals.
"Welsh rugby is enjoying a real high at the moment after the Grand Slam success of a couple of weeks ago and this will impact on all the country's professional teams.
"But we need to make sure we pay attention to detail on the night and maintain our collective concentration levels if we are to maintain our winning run."
Edinburgh (27-man squad): Hugo Southwell, Calum MacRae, Andrew Turnbull, John Houston, Ben Cairns, Matt Dey, Nick De Luca, Simon Webster, David Blair, Phil Godman, Ben Meyer, Mike Blair; Gavin Kerr, Augusto Allori, Andrew Kelly, Steve Lawrie, Craig Smith, Sean Crombie, Matt Mustchin, Ben Gissing, Fergus Pringle, Craig Hamilton, Allister Hogg (captain), Simon Cross, Ross Rennie, David Callam, Fraser McKenzie.