Ruin Explorer
Legend
Here are two gaming experiences. They are both hyper extreme to make a point. Please do not take from these examples that I'm saying either approach in D&D would go this far. It's just to help understand the general concept.
The Hard Game
I once played a Ghost Recon game where I literally real time had to crawl across a field pausing as guards passed in the distance until I reached a point where I could use a sniper rifle to take out the enemy. That crawl perhaps took 15 minutes of real time. After I took out that guard I had to crawl some more to get another shot. I had to systematically eliminate guards in a couple different guard towers. It required great care and one wrong mistake meant the enemy was alerted and the game was over. In this version of Ghost Recon, one shot often took you out. It was far closer to real life than most games. It was hard and at times someone watching me might have said it looked tedious. I did enjoy it.
The Easier Game
Call of Duty. I'm a soldier I have a really cool gun and I can run through an enemy position taking out bad guys left and right. Sure I can die if I totally ignore trouble but most of the fun is being this awesome killing machine. Watching those nazi's go down left at right as I blaze my machine gun. I get a thrill from what I am doing even though the challenge is not really there. Even if someone shoots me, I just duck around a corner for a second and I recover. The game is absolutely focused on wish fulfillment. I enjoyed this game too.
Now I like both games. If the easier game is a 1 and the hard game is a 10 on the challenge scale then I prefer a D&D game in the 7 range. I see some people liking D&D in the 3 or 4 range. No way is wrong. What is fun for you is all that really matters. Most game systems can support both styles of play well enough. It's all a DM thing. I think as a DM though it is good advice to identify how much challenge your players want to deal with. I'd never tell them I'm dialing the challenge up or down (challenge for them mind you) because part of the wish fulfillment is the illusion of challenge. Personally I don't want to run a long running campaign in the low challenge way so I seek players of like mind.
Having played both, I can say that you're confusing two issues, badly.
Ghost Recon is NOT a hard game (assuming the 2001 original). I have played it. It is a METHODICAL game. Follow the method and it is easy.
CoD is NOT a hard game (assuming one of '00s sequels). I have played it. It is a twitch/aim game. If you are good at that, it is easy.
Now, the BASELINE difficulty on CoD in particular IS much lower. But the same isn't true of otherwise-identical games - there are other action-shooters which are super-hard. It's not the gameplay that makes it easy, it's that the basic difficulty is intentionally low for a broad audience. Likewise there are games as methodical as GR but which are pretty easy.
So I think this example serves to illustrate that playstyle isn't difficulty.