The most active mappers feel that street and housenumber (and postal code, if somebody local knows it) should be enough on a building, once somebody draws the municipality borders as ways and relations. Hopefully, we’ll have them soon (soon = the licence was believed to be clear on 1st May 2012, but…) from the national mapping agency. Most mappers haven’t bothered with the house numbers at all. It’s just missing data and missing mappers.

Generally, we write addresses as
( where available) (newline)

( not really used, but last, if written)

(And, in fact, above can be “postal area name”, often a former municipality or just a smaller part of one. But even the current municipality is used in real life.)