This entry is a copy of my comment in a discussion on some of the OSM Carto rendering ideas. It's so general, that I think it makes sense to show it for more people. I have some more thoughts on this subject and I hope I will write them down too.
I believe the main obstacle for better coexistence of big cities and outdoor rendering is #1957 "equalizing" ticket being unresolved.
I think about "WMAs" (well-mapped areas), which are located in the big cities where mappers were active, that they make the biggest difference. They start to be very rich, because this is the reality, which was not well covered by mappers just a few years ago. We could rely on this incompleteness up to some point and render whatever was available without critically rethinking the whole system for years. But this is no longer true and the WMAs begin to be drastically more dense than outdoor areas. This is nobody's fault, it's just the unexpected consequence of the success of OSM in gathering all kind of data. Of course, we might stay with what we were showing before, but it's just closing eyes to avoid noticing the constant change of OSM data. Something like taking the snapshot of some past moment and refusing to take more current ones, just because it's more familiar for cartographers than trying to face these new challenges.
I like the outdoor rendering and when it doesn't hurt, I'm happy to make it also rich. There are places where we outperform typical (if not all) outdoor maps with details, like for example here:
But without some kind of equalizer (making rendering aware of a place context), it's absolutely not possible to find a visual balance between rural/urban environments. And when this inevitable moment of clash comes, I tend to care more about proper depicting WMAs than the outdoor.
There are already many outdoor maps in the wild, including some based on OSM data (Hike&Bike, OpenTopoMap, cycling maps etc.), which are better suited for such tasks as hiking, precisely because they are very limited by design. General, rich map is just not a competitor for them. And I don't even mention primary solution for such activities, which are Garmin-like devices packed with vector maps and geolocalization included.
Choosing the outdoor advantage is not just trying to play the wrong game, it also means clutter for WMAs with no hope for being readable. And these are the places where a lot of people might be interested in looking at the map. Rendering problem in the middle of Andes is still a problem, but for example visual mess in London is just much worse.
The last argument is that there are no special maps of WMAs. There might be hand-crafted maps of specific places, but no other general map style to reflect data richness. I believe they deserve to be shown as good as it's possible.