The day after Brown became the first AFL player to publicly reveal he is bisexual, Simpson said it made him question the environment within the club at the time.
Brown spoke of the "hyper-masculinity" at the Eagles when he played there until 2016, with Simpson coaching there from 2014.
"You start to reflect - and we all should do this - what was my leadership platform back then and how were we as a club with a player who was obviously going through certain things that were uncomfortable?" Simpson told SEN.
"From a leadership point of view, was I doing the right things to create the environment where you could be yourself.
"That probably just shows you that you think you're going okay, but there's always improvement.
"That's why we've all evolved - it's generational as much as it's education."
Simpson said West Coast tried to improve their environment in the middle of last decade, bringing in the "accept and care" model where players could feel more comfortable being themselves.
He suspects in a decade's time, the reflection will be that "we were old-school in 2025".
Simpson is a former North Melbourne teammate of Dani Laidley, who was outed as transgender five years ago and since has spoken at length about her experiences.
"How brave - it's fantastic ... the ability to express yourself, a lot like Dani Laidley, as well, over the years," Simpson said of Brown.
"It's just another step forward and well done for coming out."
One of the stranger outcomes of Wednesday's massive news was that the AFL's "other" retired Mitch Brown was deluged with messages about sexuality.
The "other" Brown just wanted the praise to go to the "correct" Mitch Brown.
"Some people have reached out to me under the impression that I was the one who made that announcement," the 'other' Mitch Brown, who played for Geelong, Essendon and Melbourne between 2011 and 2022, posted on social media.
"And I just want to make sure the praise and encouragement is going to the right person.
"That said, I have nothing but admiration and respect for him. His openness is an important step in making our game and community a safer, more inclusive place for everyone."
Brown, who played 94 AFL games for the Eagles between 2007 and 2016, is being hailed a hero for his disclosure.
"Mitch has shown great courage ... this is an important moment for him and for our entire game," AFL chief executive Andrew Dillon said.
Brown made his disclosure after last week's controversy when Adelaide star Izak Rankine was banned for four games because of a homophobic slur at an opponent.
"I don't believe that this is about me," the 36-year-old told The Daily Aus.
"It's not about Mitch Brown being the first at all. For me, it's about sharing my experience so others can feel seen."
An academic who has studied homophobia in the AFL and other sports over a decade believed Brown's declaration was a landmark.
Erik Denison, a behavioural scientist with Monash Faculty of Arts, said Brown was openly discussing a homophobic environment as a factor in his retirement from the AFL.
"We haven't heard that kind of direct criticism before from other players who have come out, including in rugby union and also football in Australia," Denison said.
"So this is an important turning point."
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