Will quit the series last month, making a surprise announcement three weeks into the live shows.
He cited "personal reasons" for quitting but didn't go further into his decision to suddenly leave the competition.
Speaking this week, Strictly judge Craig said it was a "shame" that Will had left and that he had "so much potential", but remarked that the celebs needed "to be ready to take criticism."
"Strictly is much harder than people think," he told the Radio Times. "It's not just a case of dancing around for a couple of minutes on a Saturday night - it's a very taxing schedule and it takes its toll physically and mentally.
"Unfortunately, not everyone can handle it - you need to be in a good, stable mental position and you have to be ready to take criticism."
There was much speculation over exactly why Will left Strictly but his pro partner Karen Clifton recently defended him.
She spoke up to support Will against various reports including that the pair 'squabbled' backstage and he had 'failed to turn up' to training sessions.
Asked if there really had been any clashes between her and Will in training, Karen declared: "Absolutely not.
"We had the best time and I love him to pieces. He was great and we always had a good time. We had the most amazing three weeks on Strictly that I'm always going to remember, and we had some great dances that will be in the history of Strictly Come Dancing."
Karen also denied claims that Will had not been putting enough effort in and had failed to turn up to rehearsals.
She explained: "He was a hard worker. He always came in and gave 150 percent. I don't think he even thought for a second that it wasn't going to be hard. I couldn't have asked for a better student."
Strictly Come Dancing is back on Saturday night on BBC One.