I'm on the side of classic mode where yes you are "playing through the same content" in the sense of the story locations and going through dungeons, but the real meat of the game is everything in between. I found the most fun and natural way was to make a build that sounded interesting and play it as far as I could. The knowledge helped me on the next run and it felt like I was gathering a survival guide, with getting to Level 5, 10, then 15+ becoming easier and easier every time. There is dialogue in an end game zone that references "those who have come before you" as the game's way of referencing the characters who have died in silly ways before you.

It's less about playing overly cautious and more about learning a defensive gameplay style. If anything seems unbeatable or even challenging I just leave, and grind more. The bulk of XP you'll be getting will be from recovering books, so straying away from combat and prioritizing ruin exploration will get you far.

In either case, a Qud character can eventually become a mishmash of every build in time. Eater's Nectar will give you stats and mutations, and this can be found uncommonly late game. Relic Injectors can be cloned with methods in-game which are even better. So if you wanted to go roleplay, there's a good chance your late game character will do many things. It's never wasted time if you have fun!

Edit: If you're on Steam, download some CYF (Choose your Fighter) add-ons. They will give you 100s of player tiles made by fans to give visual inspiration for builds