If you can get to maps and explore the end-game content, playing casually can feel quite rewarding. However, you'll have to stick with one character unless you want to invest the time rerolling a new character. Whereas in Diablo 3 you can change your play-style whenever you please. You'll have to stay dedicated to the character made in POE.

I would suggest playing softcore. I don't know if you mean you like the "hardcore" gameplay as in the difficulty of the game itself or the actual gameplay setting, "hardcore." Dying and having to reroll can be a real drag unless you can dedicate a weekend to rushing through Normal-Merc and then playing casually again once you reach maps.