Hey Mr. Kusumoto,
You are right to admonish widescreen fanatics that widescreen is only good if the movie was shot in widescreen or at least intended to be seen in widescreen (e.g. Kubrick shot films such as the shining in "full screen," i.e. exposing the entire frame, but he did this knowing that the top and bottom of the frame would be cropped, so he was framing his shots for their eventual widescreen form). And it is so unfortunate when films that were shot full frame and intended to be seen full frame are cropped into a widescreen aspect ratio to please idiots who only want to watch widescreen movies, e.g. the new DVD version of the Romero horror classic "Martin," which Romero specifically said should be seen in its full frame aspect ratio.
However, you are confused about what 35mm means, which is evident in the phrase "widescreen vs. 35mm," which exhibits a confusion of categories. 35mm is a film gauge, which may be used to photograph or project movies of any aspect ratio. Widescreen refers to a range of aspect ratios (anything greater than 1.37:1). Film gauge and image aspect ratio are two separate things. While 35mm does have a connection to the full frame aspect ratio in that, if no anamorphic lens is used, and if the image is not cropped, a frame of 35mm film will have the the full frame aspect ratio, rather than a widescreen aspect ratio. However, anamorphic lenses and cropping are commonly used. And so no film gauge can be equated with any one aspect ratio. If someone really wanted to, they could make a motion picture with the aspect ratio of Wyler's Ben-Hur (pretty much the widest of the widescreen) on 8mm film . But it would take a lot of work, and the picture would not be crisp.