Thank you all for your feedback. Let me clarify some details discussed in the replies above in more details:
We do not take any decision to deprecate a feature lightly. Before making this announcement, we checked with our Checkmk consultants and our top partners, if they are aware of any usage of this feature. The feedback was a clear no.
As the next step in the process of deprecating a feature, we placed this announcement, which will be referenced in the next Checkmk newsletter. This should help to reach more customers. I asked for a direct message if this is an issue for any of our customers. While I haven’t got any direct message, I notice 3 customers having issues with the deprecation as they left comments under the announcement.
Since the newsletter is not yet sent, I monitor the forum for more comments.
As Martin mentioned, Checkmk currently does not have any feature to collect product telemetry. Therefore, forum posts and newsletters are the only way to get feedback. But this is something we should consider for the future.