* copyleft license

Complete agree, it was stupid to move to the ODbL.

* vandalism

I've only seen once instance of serious vandalism -- I reported it on their IRC and it was updated within a few hours. And this was a mass attack by 4chan. I don't know if there's a practical way around this system. If people were vetted and had to wait before changes were accepted I think it would hurt contributions.

* Last use

I agree but all maps have the problem of getting outdated. Unless mapping is completely automated (drones+CV+ML? get on it HN) how would you avoid this?

* Inconsistent tagging

Yeah this sucks but you can deal with it at the application level usually

* Multipolygon areas

I haven't used OSM much recently but I know they did a decent overhaul with the site and the editor (the old editor was some flash tool I think). Dealing with complex polygons in software sucks so I understand why this is an issue. They should provide simple guidelines (CCW for the outside polys, CW for the inside polys), reject invalid polygons and provide a suggestion to go on IRC if they are having issues.

* Bezier curves

This is not a good idea. Why would you want to support bezier curves in map data? Its un-needed complexity. I could see support in an editor that then just creates an approximated poly line.

* One huge database

OSM is supposed to be a generic data set for many purposes. Some people might want hiking trails, others might want all the bus stops in a city, others may only want all the highways in a country, etc. Creating a system to extract and serve specific data would not only be complex it would be expensive. You'd need a lot of compute time. There are tools and tutorials for extracting what you need from the data set. There are also localized data sets available for many places (country, province/state etc).

* American volunteers

Yes its really strange that this is the case. Its impressive to see some of the places in Europe (like Germany!) and how rich the OSM data is and how active the community is compared to here. There are local meet ups in cities though where people get together and map stuff. If it interests you, you can always participate.