To be fair, the reason the right-most Raptor looks so clean is because they moved all the piping (all the complexity) to inside the casing. And the reason they made the effort is because the casing protects the tubing from the heat of re-entry. Otherwise they'd have to waste mass on heat shielding. [Take a look at videos of Superheavy Booster returning back to the launch tower--the bottom engine sections starts to glow from the heat.]

I don't think that applies to Stellarators, so there may not be an incentive to simplify it. [But what do I know; I'm just a simple programmer.]