Johnson admitted that Wales were favourites to end on a high regardless of Hogg's dismissal given that they were already 13-3 to the good and he was quick to praise the clinical nature of the 2012 and 2013 champions' attack as they finished with seven tries in total.
"They are a quality side with quality players and they moved the ball and held it well," said Johnson, after George North and Jamie Roberts grabbed a brace of tries each and Liam Williams, Taulupe Faletau and Rhodri Williams also touched down during Wales' 12th tournament win in 15 fixtures.
"Fair play to Wales, they did terrific and they scored some lovely tries. It was a tough old day to cover. Fatigue hits, so it was difficult.
"Full back is a hard position to fill for that length of time. You could probably lose a forward and cover it but it's hard to cover a back division player and once they got on a roll they played some pretty good rugby."
Hogg's withdrawal midway through the first period left Johnson with a dilemma in terms of his tactics for the remaining 57 minutes, with the former Wales caretaker coach opting against taking off a forward and bringing on a back as a replacement for the British & Irish Lions tourist.
That decision left Scotland exposed out wide as Wales ran the ball from deep and kept it alive as often as possible but Johnson felt that a change up front could have been even more unproductive given that they already lost skipper Kelly Brown to concussion with just eight minutes on the clock.
"The issue that we'd had was that we'd lost Kelly before so we'd already gone to the bench for back row cover. That compounded our issue," added Johnson. "I didn't want to finish the game with 13 - we were getting knocks as well so I was trying to cover off permutations.
"Did we think about it (taking off a forward)? Yes. But we were just trying to cover in case a few things happened. It was a difficult day to have a look and try to guess the future because we had a few bumps early.
"The Hoggy issue was compounded by the fact that he's probably our best strike runner. So not only do you lose impetus at the back and structure defensively, you lose your best strike. We lost his spark as well as his position.
"We spoke at half time about the fact that we felt we could keep the ball, just keep working and attack them down a certain edge. We showed resolve to do that but (we were punished) as soon as we turned over ball - I think it was three tries off that, with a loss of a lineout where they went the distance. That put us under a heap of pressure."
Wales head coach Warren Gatland was quick to state that Hogg's costly actions were not in keeping with the affable and professional young player he worked with on the Lions' summer tour of Hong Kong and Australia and Johnson has offered the very same assessment.
Neither man had any complaints regarding the red card but Johnson insisted that no one would be feeling worse about the incident than the 21-year-old, who has since issued a public apology.
"He's really down about it. He's an emotional lad. That emotion's a good thing and in this case he's feeling like he let the boys down. He's got to face reality that he's been caught doing something. He's in a dark place but that's just life. He has to confront that.
"It was totally out of character for the lad. He might be many things, but he's a great character and he's certainly not a dirty rugby player."