"The Israel Folau experiment at GWS was an absolute waste of money.
"It was irresponsible and dumb.
"I don't think you could ever justify signing someone from a marketing point of view."
Colless says the Swans made a decision to secure the best player when they went after Franklin - who turned down the Giants' offer of a six-year contract.
Heading into Saturday week's finals blockbuster against the Giants at ANZ Stadium, Franklin is arguably in career-best form. He hasn't missed a match this season and has booted 74 goals, just five shy of his 2014 debut season for the Swans when he claimed a third Coleman Medal.
Franklin will be in his mid-30s by time the final year of his $10m contract rolls around in 2022.
But Colless believes he can play all the way through.
"He's moving more fluently than I can recall," he said.
"You won't make nine years unless you've got a really tailored training regime but it's his passion.
"(Franklin) has been extraordinary and is genuinely a once-in-a-generation player.
"I'm not saying he's the best of all time but he lifts everyone else around him, his teammates and supporters."