Gasax
I agree with most of what you say but not with your words on older facilities
"it means you do not have to reach very deep into your pockets and pay for them to be decommissioned"
many of the earlier facilities were built in relatively small modules (due to the lack of crane capacity offshore) and are MUCH larger overall than the fields commissioned in the last 10 years
A modern field has been (partly) designed with decommissioning in mind but the older ones can be a nightmare and the de-com cost estimates are often huge