On the other hand, there is no definitive explanation for what those pipes behind that grill are supposed to actually be or do, therefore, there's no necessity that the thing has to be a long parallel structure "in real life." All we have to go on is what we see on screen or, if we'd rather, some idea of what the creator's original intent had been....
"Necessity?" What a strange standard. Why would you want it not to be? How is that in any way desirable? It was an attempt to make the engineering complex seem vaster than was possible with the available soundstage space. That's a good thing -- what possible reason could there be to resist it?
Besides, there is some canonical support for the interpretation that it's a long parallel structure -- specifically, the Constitution-class schematic featured onscreen in ENT: "In a Mirror, Darkly," which interprets the triangular pipes as the plasma conduits that connect directly to the warp nacelles. Granted, that's barely discernible in the 3D version shown onscreen, but it makes enormously more sense than FJ's interpretation of them as part of the impulse engines, because we know from multiple episodes that the dilithium crystals can be accessed from the component in the middle of the floor directly in front of the cathedral, and there's no reason there'd be dilithium crystals in the impulse engine room! It's logical that the cathedral is part of the warp engine assembly, logical that the "pipes" are the conduits going into the nacelles, and if that's the case, then they need to be parallel rather than tapered. It just makes more sense that way.