BATBFan1, Mulan wasn't changed 
back to 1.66, Mulan was never 1.66 on a US theater (unless the theater was wacked) nor was Beauty and the Beast. Believe me, I projected Mulan and The Lion King.
as for your questions, I already answered , go back and re-read my post very carefuly. examine the pics.
You're saying you're missing picture? Tell you what, even the 1.66 versions on the Laserdisc is missing "picture", as you call it. Allow me to introduce for the mullionths time the concept  of camera aperture, projector aperture and film DIMENSIONS
the CORRECT projected width of 35mm sound film is 0.825", or 20.955 millimeters. That is what's supposed to be seen that's where the groundglass lines are in the viewfinder of the camera, that's what the cameraman see and frames for and the projectionist projects on the screen .
But you think the camera shoots only 0.825"/20.955mm? Noooooooooo mr.Bond it films a little more! 5% more,  the camera hole is made a little wider, 0.866"  or 21.9964 millimeters (22mm for short) so guess what? you're missing that millimeter!!! and guess what? in the other direction, the height, same thing happens the Acadmy height is 0.600" or 15.24 millimeters. Now you think the camera is 0.600" high? Noo mr.Bond it's 0.630" or 16.002 milimeters high (16mm for short) so you're missing another millimeter there if you keep thinking like you do. The 1.85 Aspect ratio height dimension is 0.446" or 11.33 mm, Now since you want the whole image and nothing but the whole image, if you show the 22mm width you end with a 1.94 image, but then you say wait! what about the whole height? well you end up with 1.375 image!  so are we gonna watch our carefully composed 1.85 movies in 1.375?  well that's what VHSes are for! you can watch loooooooots of movies with more image anywhere on VHS.  Since DVD is a pixel perfect digital medium we prefer to see it with 100% of the carefuly composed image not 95% or 90%, or 105% like you seem to want.
You say the animators went to all the trouble to animate the bleed that falls outside the composed area. well i told you one reason. Want another? Do you think the directors and the artist are only gonna animate JUST 
exactly what they're gonna shoot with no leeway whatsoever to change the camera position? "Hey Roy, you know what? I changed my mind I actually want to show a couple more buttons down that shirt, but since we animated exactly so the edge of the animation falls on the edge of the camera, though luck, we have to spend 500,000 more redoing it" (Instead of animating more broadly and just framing exactly what you want WITH the camera's 1.85 groundglass the first time.)  Your argument would make one say, but hey, the actors brought legs to the studio, when we transfer to video this medium shot the director framed, we have to change the ratio to show the legs cus they came with the actor, after all he took several years to grow them.
And now to your very good question: why do they make some transfers show more of the vertical? like 1.66 instead of 1.85. Several  "justifications". Not reasons:
Oh new! REMASTERED! DIFFERENT! SEE wE CHANGED it. WE ShoW you MOre
Oh 1.66, Guess what? less bars! yes less black bars that every child and parent that don't know how film works, hates, whines, and complains about.
After ALL  most people still have 1.33 TVs  Not anyone has an 1.85 TV
and hey! talking about TVs, did you know that 4:3 TVs throw away 1 out of every 4 lines of a DVD to show you your widescreen movie? start with more image end with more image.
And talking about TVs, did you know that MOST TVs cut off the borders of the picture?
Called OVERSCAN?
You've heard about the TV SAFE ACTION AREA? it's 90% of the height
Here a very good Justification for the transfer done in 1.66:
if you're watching Mulan on a 16:9 TV what you see is the 1.85 FRAMING. cus the tv cropped the 10%.  1.66/1.85 = 90% 
so you're actually watching Mulan with 1.85 framing.
 Now you'll say, why then didn't they letterbox the slight 1.85 black bars if they're gonna be hidden on the TV anyway? BECAUSE the 10% is an average number, so one TV will have 8% and another will have 11% etc etc and we can't have  people seing variable black bars (in fact that's why they invented the overscan in the first place to make the picture always spill outside the tube and fill it)  but even  if the thing were so precise it matched perfectly, remember, the folks with a 4:3 TV would get thicker black bars if they do it 1.85 instead of 1.66 (like they do with Beauty And The Beast) (And look! you're complaining! so you prove the wrong version right!)  Now look at the Mulan pic. Is that empty space above the dude's head so important to see? Is his pant important? Is one of two Mulan unused arrows important? For the scene?? No, in that scene Mulan made a bubu and what's part of the scene what were suposed to experience is him peering over and looking at her reprehensively and she smiling as oops i did it again.  smile. and that's best served with a close thing medium shot.
 Hope it starts to make sense cus you're loosing sleep over nothing. I even think you could see on the Work in Progress Laserdisc (yes i have it) the 1.85 framing rectangle lines on the art, and I remember thinking, why didn't they crop the transfer to that! the correct framing just like i saw it recently on the theater? before i started to seriously think about all this compromises home video editions do and now i pass this info to you.
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