The Mimic chest is a single "gotcha" which is only unfair the very first time but after that it's on you to be noticing the difference and taking a test swing at new chests. After you know it happens you can predict it and deal with it every time, which is what Dark Souls gets its praise for. In fact the bloodstains, ghosts and messages means that it may not even happen to you once.
I agree that it's unfair but I think it works well to reinforce the feeling that you're always in danger and everything in Lordran hates you and wants you dead. It teaches you something new about the game the fact that it's also pretty unambiguously unfair means that you aren't left you with the nagging feeling that you got something wrong without understanding why, I think it's this feeling that we really hate when we criticise a game's unfairness. So I suppose yes unfairness can sometimes make a game better but it needs to be used sparingly and preferably in one-off situations.
The Anor Londo Archers can go fuck themselves though, they really are unfair!
I agree that it's unfair but I think it works well to reinforce the feeling that you're always in danger and everything in Lordran hates you and wants you dead. It teaches you something new about the game the fact that it's also pretty unambiguously unfair means that you aren't left you with the nagging feeling that you got something wrong without understanding why, I think it's this feeling that we really hate when we criticise a game's unfairness. So I suppose yes unfairness can sometimes make a game better but it needs to be used sparingly and preferably in one-off situations.
The Anor Londo Archers can go fuck themselves though, they really are unfair!