Actually, for many folks I think it does indeed have a lot to do with the monitor they're using, and its native resolution. No, that doesn't affect the basic fact that the graphics are not Windows native (in that they don't scale with resolution), and yes, the graphic style is quite a bit different than a lot of other 2D wargames out there. But if you find the graphics blocky or imprecise, that effect will be accentuated by LCD monitors with resolutions that aren't the same (or scalable to) the game's resolution.
Personally, I'm more of a fan of crisper but plainer military symbology, but I've grown accustomed to the SSG style and it certainly doesn't affect my enjoyment of the game. It's a different aesthetic, not just a matter of old tech, I think. YMMMV.
The blocky pixelated look of this game engine has absolutely nothing to do with monitor resolution or zoom level. Look, for example, at the Avatar image for Joe98. Notice the zigzag staircase effect of the diagonal lines and the lack of smooth transitions during color blends. It's obvious that SSG is still using an old graphics engine that was ported over to Windows ages ago.
Now look at this screenshot from War in the East. http://www.matrixgames.com/forums/tm.asp?m=2410710#
See how crisp the graphics are on the icons. See how the diagonal lines show no stair-step effect. This is what a native Windows graphics engine looks like.
I'd love to play Across the Dnepr. But I can't endure graphics that look like they are from a DOS game circa 1999.