We've all seen what WC fighters look like if they make a movie out of the game, so...no thanks.
Actually, the WC3 and four fighters were not that lowpoly. They were in a poly range between 150-400 polies, so just slightly less than the FS1 poly range for fighters.
As for extruding metal plates...we use that for our capships(frankly, these were really low poly since they had turrets antennaes and stuff, so they had to keep the polies of the main body low), but for most of the fighters it doesn't really fit IMO. Think of nowadays fighter planes - they all have smooth surfaces - imagine a F16 with those extruding armor sections tucked on - it would look strange.
And many of the WC ships are inspired by diverse fighter plane designs(especially in WC2), though not so much modelwise in WC3&4, but texturewise where the paint shemes are inspired by the US navy planes(the WC team even visited an aircraft carrier back in '94 or so to study it upclose)
Plus the edginess of the WC3 designs is the design way, not just because the older computers couldn't manange so much polies. you could do smooth ships back then(see the original Arrow for example), and they could have faked those minor details with textures, since with the low screen resolutions used( 320x 200 and 640x480) it would have looked good and real, but the design team choose not to. And who are we to question ORIGIN Inc(may it rest in peace)
To me it doesn't really matter how detailed a ship is as long as it looks 'real' in a way, which I hope made with my textures. There are a lot of examples of high detailed ships all over the game worlds that look less 'real'(me gets an uneasy feeling when using real in connection with FS
)