Why does Voyager have moving warp nacelles?

...and why is it the ONLY ship we see with that?  I figured it out.  If you're not into Star Trek, this is gonna be a rough ride and maybe you should skip this one.

Back in the last season of Star Trek:The Next Generation, there was an episode "Force of Nature".  It was TNG's global warming/environmentalism episode and the basic idea was that warp drives were causing damage to the structure of space.  The ships all needed to stick to a speed limit after that until the ships could be fixed.  So a little but after, we get Star Trek:Lost In Space and the USS Voyager now has moving warp nacelles.  "It's because of the environment!" they told us.  This was a direct response to 'Force of Nature', and sure, I guess, that makes sense...  maybe they need to move the nacelles around to tune the space blenders right, I get it.  But....  none of the other ships we've seen afterwards have had this.  Why is that?  Why is Voyager the only ship that does this? I FIGURED IT OUT.  Sure, I figured it out 19 years later, but I figured it out. Clearly, Intrepid was a ship that was too far along in the design phase to have all the relevant info learned from the subspace damage incident incorporated into the design.  They've been putting together the first ship for months/years and suddenly....  environmental impact statement hits and everyone's wondering how this ship is going to deal with it because it'd be a little awkward to put out a shiny new ship that breaks space right after announcing everyone else needs to slow down so they don't break space. SCENE: (A pair of designers stand in front of the blueprints, the half completed hull of the USS Intrepid visible through a window. The space janitor is mopping the floor behind them) Designer 2: "If we move the nacelles to here, then it screws up our impulse maneuvering. If we move it there, we end up with a 'dirty drive' that keeps screwing up subspace. What do we do?" Designer 1: "We can't stop the construction, BuShips will have our heads. We already work in some sort of fairyland kinda post-scarcity economy, we can't afford to be BAD at our easy jobs too!" Designer 2: "This is bad, this is really bad. I was going to retire to Risa, but how can I do that if I can't make enough Federation reputation points here to convert to latinum?!" Designer 1, manipulating projected blueprints floating in front of him: "THAT'S how we buy stuff from other cultures? They should really talk about that once in a while. Oh heck, I don't know what we're going to do about this. The warp nacelles HAVE to be up here for clean warp, but they have to be down here for impulse flight otherwise the damn thing will wallow like some sort of garbage scow." Designer 2: "We're doomed!" The space janitor speaks up, turning off his electromop. "Uh, you guys ever hear of hinges?" The scientists turn to him, mouths agape. "Hinges? What in the seven moons of Targon III are those?" Janitor: "First, nobody talks that way. Second, I'm part of a historical re-enactment society. We re-enact films that used to be made in the San Fernando Valley of California that involve human pool cleaners, human pizza delivery drivers, human viewscreen repair technicians... it's very authentic!" Designer 1: "And they have some sort of warp field manipulation device we can use?" Designer 2: "What were these films about?" Janitor, hurriedly: "Never mind about the films, and no, they didn't manipulate warp fields exactly. Hinges are devices that their doors would swing on. I bet you could put a pair of of those things on the bottom of one of those warp stick things no problem." Designer 1, shrugging: "Computer, mount the warp nacelles on giant 'hinges' (he makes air quotes as he says it) appropriate to the anticipated loads and show us how they could be used to adjust the warp field to meet these new requirements yet maintain maneuverability at impulse." Designer 2, nodding: "Run program." Space Janitor: "Do you guys actually need to know anything? Or does the computer do all the work?" Designer 1 and 2: "Quiet, you!"