You're out of luck. Even master, after a certain point becomes easy simply by making an optimal character. Just accept that Beth can't make challenging or balanced games if their lives depended on it.
I don't know that Bethesda is trying to make a "challenging" game, and balancing is near impossible when you have an infinite number of playstyles.
Bethesda gives you a canvas, and you can paint your game however you want. If they did what some people want- and made the game very challenging even for optimal builds- it would force players into playing a specific type of character.
But maybe you want to play a different way... maybe you want a little- you know-
roleplaying in your RPG. Perhaps you're an Orc who refuses to use anything but Orcish weapons, and won't enchant them because you believe it dishonors the blade. Or maybe your wood elf ranger believes his only clothing should come from the animals he kills, so you never go above leather armor and his hunting bow. Perhaps you want to go full conjurer mage who lets his undead armies fight for him, and you never put the points into other areas. Maybe you're an Imperial, who will only wear his military armor and wield his Imperial sword, or a true Daughter of Skyrim who won't part with her steel Nordic armor.
Bethesda's challenge is to make a game that's fun and playable for millions of players playing millions of different types of characters. So sometimes you have to adjust the difficulty mid-game. Sometimes you have to play it out on the easiest level. I'm fine with that. It's better than knowing I can only succeed if I go "Duel weild sword, heavy armour + smithing," because that's the last character type I'd like to play.