"The halo affect you have to consider is that the games will be far more entertaining. Some of the rugby I watched over the weekend, you're visibly seeing players pull out of a tackle, because they think 'I'm in danger here'.
"With that, more rugby will be played."
Players and fans have been quick to bemoan the immediate impact on games.
In the Aviva Premiership, defending champions Saracens held on for a 13-13 draw against Exeter, despite losing prop Richard Barrington to a red card for another marginal tackle offence, albeit a tackle that saw Exeter lock Geoff Parling stretchered from the field with concussion.
In Guinness PRO 12 play, Scarlets edged Ulster 16-13 on a penalty try, awarded when an Ulster defender made almost incidental contact to the head of a player lunging for the try-line.
"I think that's fair enough," he said, watching the Ulster incident. "It's irrelevant if you slip or trip or fall into it.
"This is being done for the right reason. There will be some inconsistencies early on, but you either be a Luddite, bury your head in the sand and moan about absolutely every decision or accept that World Rugby authorities are trying their best to make this a zero-tolerance area, a no-go area, a safer area for friends and players and family to play in.
"At the same time, we will be creating an increasingly attractive game, a game that is already on the up."
In meantime, Greenwood suggested coaches work with referees to understand the new directives and with their players to correct tackling deficiencies in the new environment.
"This is absolutely a net win across the board," insisted Greenwood. "Short term, stop your whinging and moaning, and understand you might have a different view on it, but they're not cheating.
"They're human referees, trying to interpret these laws as best they can, when players are travelling at 25m/h, carrying 19 stone."
