Linear, linear, linear

[Payadopa]

And what did the player base decide about those dungeons? Since the rewards and bosses would be the same regardless of what order you did them in, the player base decided that the 3214 order was the most efficient route so every group would automatically go 3214. The occasional random player who wanted to go 1324 would get left for dead at best if they didn't rejoin the rest of the group or kicked out of the group at worst.

At that point, the dungeon might as well be linear when groups are going to follow the same route every time regardless. There's nothing gained (or lost) by going a different route outside of an extra minute of time.

Variant has a nice concept that's the start to making multi-path dungeons interesting but there's still a lot of room for improvement. Imagine alternate paths that lead to altars that grant a group buffs, with those buffs granting different benefits to the group at the same time they subtly alter boss mechanics (as we see in the current Variant based on route choice or interaction with various objects). Groups would could choose their route depending on which buff would be most beneficial to the group comp's strengths and weaknesses since the Variant actions make the usual T-H-D-D comp unnecessary. Or perhaps route choice would change what the boss loot drops are. Defeating optional bosses could make the final boss harder with better rewards or weaker with lesser rewards.

There's no point in making multi-path dungeons if the choice of route doesn't have the potential to impact the overall experience in some meaningful way.

So the logic is because it'll get eventually boring don't try to change that and make it boring from the beginning.

Why have interesting abilities when someone will do the math and figure out the exact best rotation. Why figure out a boss fight yourself when you can watch a YT video.

The answer is always the same. Because some people enjoy it and play for fun.