Newsprint probably carries a higher expense because nobody does it. You need to find a shop that can fit you into its schedule and cover the start-up cost for their plant. If the industry changed, there'd be contracts that would drive the price to a competitive level, I'm sure.
As for the paper change, since I brought it up, I guess I should quickly run down the list of things I think went wrong when better paper became available.
- The bleed: Being able to draw to the edge of the paper has provided some innovative panel arrangements, but it's mostly responsible for two-page splash panels that convey nothing and/or inter-panel art that muddies the action. The splash panels then lead to decompression, the misguided idea that comic books are like movies and the way to show passage of time is to have many panels where people stand around not doing anything interesting (or for continuity of motion--no, no, I get how the pen got to the floor from the table!).
- Faux-collectability: Sturdier paper suggested the collectors' market by making them an "investment," making it responsible for millions of "gimmick" issues and covers, while anybody with half a brain realized that old comics were worth money because they were hard to maintain.
- Lazy art: Seems like every time in the last ten years I've opened a book that so much as mentioned outer space, we've Photoshopped the background of at least one panel to use NASA stock. The effect is invariably jarring, rather than smooth. A problem with Photoshop, maybe? Perhaps, but I don't think anybody would try for that kind of "quality" on crappy paper.
- Fussy art: Along the same lines as satellite pictures of Earth, we all remember the fiasco of Wonder Woman's new costume? The one that I'm pretty sure already never existed? My problem with it is that every dang bit of it is covered in scritchy-scratchy filigree. That sort of detail would never survive to the printed page without modern paper, so no artist would even try it. And that example only stands in for decades of "constipation lines" on the scrunched-up faces of characters and cross-hatching everywhere.
- Lack of restriction: It's been said that the Hulk would have been gray or brown, had it not been for the fact that he was impossible to print consistently that way, and I don't think he'd be an icon if he were. Today, artists (often) don't bother to worry about how something will look to the reader, because "what you see is what you get." And what you get is a lot of poorly-planned trash.
- Glare: Like Kevin, reading from glossy paper bothers my eyes and makes it hard to take the entire page in at once, since the glare shifts.
I think that's it...and not to take away from Jim's points, since he's got a different purpose in mind when he reads the scans.
(Now, let's never talk about computer coloring or using standardized fonts for lettering, OK...?)