TL;DR: Yes, it is intentionally different. Stay calm.
I’ll make one thing clear: Yes, it is different to the other Torchlight titles. No, it isn’t actually inherently horrible because of this like so many hysterical Steam Users are so quick to claim.
There have been many different isometric dungeon crawlers to come and go through the history of video games, and many of them have been very samey. I, for one, am actually very glad to see Torchlight III get away from so many of the codified tropes of the genre.
If you want nine-thousand hours worth of postgame and a spreadsheet of skills extensive enough to put Gary Gygax to shame, play Grim Dawn.
If you want a solid singleplayer Diablo-like for Steam that’s still receiving dev support, play Titan Quest Anniversary Edition.
If you want a workhorse stats-and-loot grinder that runs perfectly fine on older systems, play Fate.
If all you’re after is more of the same you got in Torchlight and Torchlight II, go and play those (or any of the endless mods for them) instead! Don’t come to this game and bemoan it because just because it’s trying something new. (Especially not if you’re someone who has come to their negative opinion based off the word of a games journalist or eceleb, who themselves must have played only the pre-release alpha at this point.)
For the record - Torchlight III does something new for both its series and its genre of game, and it does it well.