Sometimes, we want to create a release board (separate from the backlog) to start planning a release/grouping features. We don't know the release date until later. Rather than create a fake date (which can cause this to get lost in other releases), I would like to be able to leave the release date blank and come and fill it in later once we have finished planning and sizings.
As you had described, you can achieve the same goal with the workarounds that you had mentioned
We understand the planning period for releases and built the parking lot in mind for this use case. While we understand the potential use case of wanting to create a planned release without a release date, we are unlikely to create additional functionality here (since it can already be achieved with the parking lot). We plan to mark this idea as "already exists" given the parking lot.