First, we should discuss this in English. Second, it doesn't matter what other maps do, we have our own rules in OSM.

If there is a difference in opinion of how something is to be mapped, that's okay, then we should discuss that. But a change of this magnitude isn't something that you can just do without discussion.

As a side effect of this change the coastline processing is currently stalled which means that most OSM maps worldwide will not get updates to any coastline worldwide until this is resolved. That is not a good situation. So please revert this change and then start a discussion on the community forum about the different interpretation of where the coastline should be.