Whether we should tag streets indicating whether it has an associated footway/cycleway is a discussion that comes up again and again on OpenStreetMap forums. Currently there's an ongoing discussion on the mailing list for Denmark discussing whether or not the cycleways in Copenhagen should be represented as cycleway=lane tags on the streets or as separate highway=cycleway ways alongside the street.

Rather than discuss that specific issue I think it's worth stepping back and thinking about it makes sense to represent the sort of complex map data we're likely to get in the future where we want to accurately represent highways, pedestrian areas, intersections and other things like that.

Right now most intersections in OSM look like this:

These ways may or may not have an associated pedestrian pavement.

Here's the same intersection with added pedestrian ways & crossings:

No tags on the way (within reason) are going to intuitively represent where I should cross the street without making separate ways. It's also easy to add to the map where e.g. a button I can press to activate the pedestrian crossing is.

And this is what I think OSM should look like in The Future:

Here we have an intersection with pedestrian ways alongside the road & areas for both the road and the pedestrian areas (if this was accurate enough you could automatically drive an RC car with OSM data). There's a cycleway on the street that has been mapped separately, although not as an area because I was lazy when making this example.

Someone who doesn't want to do intelligent routing can just ignore all these fancy areas and just use highway=* ways which aren't areas. This is the case with rivers/riverbanks at the moment where we support both:

But would anyone be crazy enough to map everything as areas? Yes, this is how traditional GIS databases have been maintained for decades, here's an example of an intersection from Reykjavík, Iceland in LUKR: