I don't see why Marner should/would feel guilty. Every top paid guy could have taken 500k less and the team would be in a better cap situation. I'm sure the other 3 don't feel guilty.
Why would any other player feel animosity towards Marner? He negotiated his salary, ultimately found a number that both he and the Leafs were comfortable with, and now makes that much money. That is the same thing that those other players did. In the case of Kapanen and Johnsson, I feel that they were both grossly overpaid as well and are gone based on their inflated salaries.
Marner scored at 1.13ppg pace last season. In a full 82 game season that's good for 93 points. The previous season, he scored at a 1.14ppg pace. How can we be really upset by this? By all accounts, he had an off year last year and still put up 67 points in 59 games. He tied for 19th in scoring in the NHL with Alexander Ovechkin(in 10 less games). If his goals would have actually came would we even be having this conversation? Please keep in mind that not only did Marner have a "poor" season, the team as a whole had a season that was poor. Tough to keep pinning that on a 22 year old.