commented by cbkiyanda (2017-03-02 02:21:29+00:00): I've replied to a note with a similar objection (in french) in the village neighborhood, so the discussion will be doubled for a little bit until we find a good, single place to discuss the issue.

I think there are three related, but separate issues raised in the above comments: 1) what properly belongs in osm data, 2) what's the point of tagging sidewalks and building entrances separately, 3) should sidewalks be tagged separately.

I'll address those 3 points in that order as, I think, that's from easiest to address to hardest to address.

1) Are sidewalks worthy of being mapped in OSM: I say yes. There is no guideline of what constitutes a worthy detail to include in the data or not. If that data represents a feature that has a "constant" geographical location, a case can be made to include it into OSM. I personally think including trash cans is useless. I have a friend who loves to tag trash cans. The ones that are bolted to street lamps are "fixed" and hence belong into OSM. I (and many others) believe sidewalk (and associated) information belongs in OSM. 
2) What's the point of tagging sidewalks and building entrances? Routing for disability is a thing and a lot of information is useful for that purpose. Improving the data so that better accessibility routing can be achieved is a meaningful goal. I just have a personal interest, but there are university research groups developing such routing engines as part of high-level research. It also benefits real people. It's often surprising to able-bodied people that a single tag "accessibility = yes/no" wouldn't be sufficient to encompass the whole range and required granularity for accessible routing, but it's not. A given slope on a sidewalk may make it impassable to people using a walker, but fine for someone on a motorized wheelchair. That's just a single example. What do you do if a sidewalk has a distinct slope from that of the street? There's a whole osm disability mailing list if you want to learn more.
3) Should sidewalks be represented as separate objects from the street? Now, that's a good question. Currently, both approaches coexist in openstreetmap. Tagging sidewalks as metadata on a street actually has drawbacks. The idea of tagging sidewalks as separate is not new. That's been recognized in 2011[1]. The issue of how to map sdiewalks is described on the main wiki page for sidewalk [2]. Both are definitely valid, as help.openstreetmap [3] also says. I think everybody recognizes the drawback of having separate sidewalks on current renderers. There's a draft proposition of uniformizing the sidewalk encoding schema from june 2016 [4] to which I'll contribute now that I've found it.

I realize there's an impact on current renderers and routers of adding the granularity of sidewalks to the data. I think everybody recognizes that. The questions are "can all use cases be represented with sidewalks as metadata?" and "what's the best way to represent sidewalks?" Respecting the osm tradition of not tagging for renderers/application, I would suggest that the issue of "harder to read" is for the renderers to deal with. Sidewalks are recognizable as having the combination of {highway = footway} and {footway = sidewalk}. Should be simple enough to exclude those from render.

[1] https://wiki.openstreetmap.org/wiki/Proposed_features/Sidewalk_as_separate_way
[2] https://wiki.openstreetmap.org/wiki/Sidewalks#How_to_map
[3] https://help.openstreetmap.org/questions/1236/should-i-map-sidewalks
[4] http://wiki.openstreetmap.org/wiki/Proposed_features/sidewalk_schema