While my needs are not the same, I to have found the inability to update assets via API somewhat frustrating.
Our use case as of late, is trying to update assets records from various platforms. For our servers, we are attempting to populate the "Last Backup Date" when our nightly backup process completes. For all assets, we are trying to populate the "Last Patched" field and another custom field from data we are pulling out of our vulnerability scanning tool (Nessus).
We also have a few custom fields that we'd like to populate with data based on a calculation from other fields already published within the asset. Lansweeper doesn't allow this, but we think we could make this work via API as well.
We try to make lansweeper our "system of record", and for the most part we can. At least in my line of work, there is a growing expectation in regards to the amount of reporting we are providing to management. That transition has required us to populate additional fields in Lansweeper that we previously didn't care about.
The ability to update fields via API is really the only way I think we are going to be able to keep up with these requirements long-term. We are really hoping this makes it to the roadmap in the near future.