The beauty of D&D is the simple fact that it is fantasy. You are these fantastical heroes to the world. Your every breath goes into shaping and changing the very fabric of the future. Your decisions are felt for generations.

That applies to every other High-Fantasy RPG, too. DnD hasn't created the genre.

lol actually after my arguments, I see your point. I simplified D&D for my group. I made it so that everything they needed was on just a few pages. I didn't need to change the rules to do it, I just compiled them differently than WotC.

If you have to do this it's not a good system. See my Shadowrun Rant – Shadowrun5E required me to compile the rules myself. It ended up in 23 pages of rules explanation.
At least you don't have to do it in order to understand DnD 5E – you just did it, in order to make the rules easy to understand for beginners.
Why do this in the first place, when you could save your time playing easier games like Dungeon World? Inertia, and popularity. Everyone played DnD before, so we'll also play DnD.

and the odds are easy to calculate as every bonus is a 5% increase.

If you want a game where maths and balancing are an important thing, the d20 helps by being 5% increments (but it also adds the stupidity of nat-1/nat-20 as I mentioned in the OP).
Does everyone like games where maths and balancing are an important thing? Hell no! … At least I don't.

The fantasy feel leaves a very lighthearted feeling that is relaxing to me and my group.

This applies to most High-Fantasy games, again (unless you're playing a grimdark system like Zweihänder – but then you knowingly signed up for grimdark).