Well... yes. A bit...
True, some genuinely nice bikes just happen to have down pipes (the KX250 again), but for me the downpipe is a part of what makes them attractive. I dunno why. I especially like those downpipes that dump into a single integrated cylindrical muffler, like the Circle F pipe I had on my TM125. And some of those pipes on the dirt trackers, very nice.
Now don't misunderstand, I'm not pinning posters of CR125s or KX250s on the dunny door, I just like the look. It works for me. It somehow gives a bike a certain feel or emotional cue that a bike with an up pipe doesn't have. I love the look of say a 79 CR250, or 80 YZ250G, or Kent Howerton's works RM, but the pipe is not part of what makes those things look good.