If you ask me, a fan design like you described--and like how most of the displayed designs--is as fanboy-ish as the Sovereign-class in my opinion. I'm sorry but I prefer the Intrepid-class as is. Your non-suspension of disbelief of the idea that warp engines can be compacted is what's causing you distaste. It would also seem that disbelief and skeptism is what's helping cause a stereotypical taste of starship design in Trek-fandom world-wide.
The Galaxy-class for its size has small engines... Designs like that, or the Nebula-class, is what TNG designs are all about, even in evolution. There are designs like the Intrepid-class--or even the popular Defiant-class--that help prove that Starfleet is moving on the right track in starship design, that they care less about big bulky nacelles and popular fanciful looks and more about compacting technology while keeping efficiency. In my opinion, Intrepid-class warp engines are potentially more-advanced than the Sovereign-class's because of it's lack of need of big nacelles. It can achieve a Warp 9.9 velocity with those little compact nacelles. I believe whatever technology we--as in the Human race--produce, it will get smaller and more-efficient over time. Maybe in the 24th century we would have space ships like the Intrepid-class, with engine travel as efficient, yet compact like the Intrepid-class. Your disbelief is like disbelieving the existance flat-screen TVs or monitors, even thin notebooks/laptop computers.
Designs like the Sovereign-class are too fanboy-ish, as in bulky, long nacelles and a hot rod-like design with all these torpedo launchers located all over the ship. I wonder what starfleet engineers were thinking in some designs like the Sovereign-class, or oversizing Pereguine-class ships and kitbashing them with intrepid-class hulls on 'em, or mixing Excelsior-class Carrier variants with constitution-class engines... I never got that.
I appreciate your thoughts ... though oddly enough ... NONE of my opinions are based on the size of the nacelles or stereo typed idealisms. Sorry, sir, but this is one where ya kinda missed the mark on my behalf.
And simply because a Federation ship is capable of defending itself is no reason to categorize things as fanboyish. Heck for that matter the Defiant that you refer to as a popular ship is in fact one of my favorites... I LOVE its speed and defensive capabilities. Also if you look at many of my designs the nacelles are more compact, located a bit closer to the primary hull ... and frequently based upon the idea of "advanced" development in their over all capabilities. ( See X-CLC; ADD and AAC for examples)
My overall dislike of the ships mentioned above ... Promey ... Voyager .. and Akira is more like:
1. Promey : Star Wars marries with Star Trek .. an overly simplified review perhaps .. but AGAIN .. just my own view point ( of which I'm certain that many will disagree with .. but hey ... that's cool ! After all Paramount did not ask me what I thought on the subject ... and I'm almost certain they could care less)
2. Voyager : over all ok .. but seems like they just took some short cuts in the wrong places and could use a little face lift here and there ...
3. Akira... How on earth people see this as an updated Miranda (though that is what we are told) ... it looks more like an after thought. Parts of it just thrown togeather. Frankly the NX-1 looks better appearance wise .. If they wanted make another up-dated version of the Akira ... and use the NX-1 as a model I personally have no problem with that .. call it an NX-1 descendant ... give it an appropriate name still call it an Akira... that's cool ( I know .. I know .. this is touching the "Holy Grail" .. and upsets some of ya ... But I hope that a couple will see past some of the usual arguments that take place and see the bigger picture here)
Back to the topic at hand ... some times stretching the nacelles ... bridge ... pylons ... other areas is needed in order to make the model "flow" better .. give it the "right stuff" ... and her design lines seemingly just simply works better. Sometimes shortening them is better. Take a look at the Galaxy Class..... can you imagine it with Sovereign styled nacelles... (ecch .. shutters ...And yes ... a lot of this is personal taste.)
Just for fun... why not take a crack at a few sketches ... if we find one it might get built ..... If not then what the heck.
Remember: If ya aim at NOTHING ... you will hit it EVERY TIME !!
OH ... BTW.. this really is not a rant.. if taken that way .. sorry !