Kevin Schade's 18th minute goal was enough for the Bees to win at Portman Road on Saturday.
The game was marred by several VAR stoppages, including in the lead-up to the goal.
“I think it was two teams being physical in the box,” said McKenna, when asked about the interventions of VAR. “Both looking to work blocks, both being physical and, for me, VAR in general, we won’t have it next season as as club, I’ve spoken about it earlier in the season, I don’t think it’s adding.
“In its current guise I don’t think it’s adding to the game. Of course, there are some benefits to it, but we’ve had quite a few games like that this year.
“We had it two weeks ago at Newcastle where the game’s been stopped for two, three, four minutes to look at marginal calls that you can never say are clear and obvious. If it was clear and obvious, it could be looked at in three or four seconds and say it’s a decision or not.
“But with it being stopped, supporters in the stadium are standing around or sitting in silence, players are standing around, staff are standing around waiting while things are getting reviewed for minutes on end that are marginal decisions.
“The actual things that went on in the penalty box, they were probably similar for both teams. Both teams had appeals, the referee decided that none of them were strong enough cases to be a penalty.
“The pauses in the game that come, both on set plays but on other incidents, in my opinion, are taking away from the game as a spectacle for the people in the stadium and for those involved.”
We must learn from Brentford
Beyond his frustrations with VAR, McKenna said of the game: “I think we certainly could have got one. I thought the players gave everything. I think we competed as well as we could.
“We know we’re coming into it in really difficult circumstances against a team in really good flow with a consistent team who have played together for the last few games and played together for a lot longer than our team on the pitch now has.
“I thought we competed well. Of course, the first goal is big in these games and if you take out the other incidents, it’s a good set play from Brentford and they’ve done it terrifically for a lot of years now, and we have to learn and work to improve.
“But they’ve built that up over probably a decade in terms of their set play processes and culture.
“So they score a really good set play goal, which is one of the reasons they are where they are.
“I thought we managed the difficult bits of the game well, better than we have in the last few home games. I thought when the game was getting away from us, we didn’t lose our heads and go chasing it, we managed to stay in the game, which has sometimes been a little bit of a problem in the home games."