Langford, a Fonterra supplier who farms at Golden Bay, said the news had come as "a little bit of a shock" but that he wished Wilson well in his recovery.
He said the decision, together with the news that Monaghan would step in as chairman, would remove some uncertainty in the leadup to board elections.
"It answers the question that a lot of people were asking as to whether John was going to stay on or not," he said.
Wilson's time in the chair has been tumultuous, almost from the outset.
Less than a year after taking over from previous chairman Sir Henry van der Heyden, Wilson found himself in thick of a serious food safety issue in the form of WPC80 false botulism scare and precautionary product recall late in 2013.
The scare ended up costing Fonterra $183 million in compensation to French food giant Danone.
Extreme volatility in world dairy markets followed, with Fonterra's farmate milk price hitting a record $8.40/kg in 2013/14 before slumping to well below break-even in each of the ensuring two seasons.
Many farmers were dangerously close to failing before Fonterra came up with a soft loan scheme, which was enthusiatically taken up by the majority of its members.
Then came the $755m purchase of an $18.8 per cent stake in China's Beingmate Baby and Child in early in 2015 - a company that has struggled to perform since.
Fonterra chief executive Theo Spierings and chairman John Wilson. Picture / Jason Oxenham
Langford said WPC80 and Beingmate had been disappointing.
"But on the other hand, if we look at some of the positives, John was a really strong advocate of the farmers support loan during the low payout years," Langford said.
"That helped a lot of farmers get through - and that was for mums and dads down to the new share milkers as well," he said.
"One of John's strengths was that he was a dairy farmer who spoke for dairy farmers - sometimes quite bluntly - and I see that as a strength," he said.
