As for why Gone With the Wind a 60+ year old movie can look so perfect compared to todays? Lazario, i dont remember for certain if I saw The Kiss in theaters (too long ago) but at least i saw it somewhere and i don't remember grain (like as omg this film is grainy) but i also don't remember the opening scene. Maybe it has intentional grain?
Anyway, The Kiss was shot on (i think) Standart 35mm USA 1.85 Widescreen color negative and that makes its physical dimension height to be 11.33mm, while Gone With the Wind, just like Disney 35mm Academy ratio movies, was shot with a negative height dimension of 15.24mm. Not only that, but it was shot in B/W film Technicolor (again like Disney animation) so each frame is recorded on three negatives and for the DVD they used the Ultra Resolution method supposedly deriving the color image from the b/w separations, therefore (excuse the math) a square area of The Kiss color negative has 11.33 x 11.33 mm = 128 square millimeters, while one in Gone With The Wind has 15.24 x 15.24 mm = 232 square millimeters MULTIPLIED by THREE = 698 square millimeters
698/128 = 5+
So all else being equal the Gone With The Wind negative would have 5 times less the grain, of course it's different emulsions and etc, but film real state is always film real state and also b/w film theoreticaly used to be better than color, etc, etc yadda yadda mew.
Also in addition to that, GonieWindy has been Lowrysized, and he has his own propietary methods of getting the image separated from the grain and if i told you how he'd have to kill me
The video transfer from The Kiss might have been made from the negative but also could been made from copies of it like interpositives, internegatives, or even a print? and each adds more grain so that could be a reason too.
(And here, since everybody seems to think this, I'll mention again this misconception that for a DVD you have to have or make a nice
print, which is wrong, it isn't so! If you have the negative or intermediates you don't have to have or make a good print, scan the negative! it looks better!

Stop thinking that there has to be a good print surviving (or made) only, to do a video transfer. Prints basically are needed to watch a movie. On a film projector.

. )
See how good Gone With The Wind is. No print.
to paraphase Lazario's question:
Can the studio accomplish a nice-looking VIDEO for an affordable cost?
For that see netty's post
But of course the studio may not have the good film elements survving, the resources, or the "will" (more $$$?) to do it.