Is it possible for a game you consider easy to be good?
To some degree, yes. I’d like to cite Kirby here. Being challenging is one of the primary factors I consider in rating a game, and I have certainly penalized games for not being hard enough before.
Being easy is a negative mark in my books, but a game can be easy and still have a large non-redundant state size. DMC4 has an easy mode after all. (And so does Dark Souls, it’s called, NG, lol). However difficulty is partially attached to my definition of depth. If a game is easy, then the choices involved in solving a problem may be trivialized. The range of states that a less skilled player may go through isn’t relevant to a player of your skill level. There’s also a tendency for there to be a lower range of states when a game is tuned to be easy. If you can kill enemies in one blow, then you don’t need to go through prolonged battles or worry about trading hits or avoiding their blows. Those states still technically exist, but because of the tuning of the game, they’re not relevant to you. Though states involving the enemy being in hitstun, or having intermediary levels of health or progressive status conditions related to being hit repeatedly, those won’t exist anymore.
Kirby has a lot of different powers that all work extremely differently, and far as I can remember, play on my 4 criteria for depth a lot. It has enemies that fit this pattern too. Kirby is also tuned to be extremely easy, however Kirby is still an interesting game series because it’s well designed in all other respects. So I do knock it a bit for being easy, but I still respect it.
What about the newest Zelda of MGSV? They are not particularly challenging and in case of MGSV (or any MGS since second one) you can easily beat the game with tranq pistol “strategy” without being meaningfully challenged to change that. We can argue that MGSV adds helmets and armor vests to their enemies later which makes tranqualizer guns less effective but still it is fairly easy to be effective with them for the rest of the game.
And how it plays into idea of for example “immersive sim” games that their challenge is really just an obstacle like group of enemies, getting from point A to point B in a room full of traps or whatever that can be solved in multiple ways and game doesn’t really force or gets you into particular solution (people often even come up with extremely inefficient solutions because it’s fun or looks cool rather than take what’s most effective or intuitive and it also applies to games I mentioned above).