Unlike A1 content on A2, A2/OA/DLC content loaded in the A3 engine looks good enough with config changes to be worthwhile to play on. It would be nice in official release if A3 came with A2/OA/DLC lite content (for multiplayer compatibility) and automatically mounted A2/OA/DLC content if you owned A2/OA/DLC.
This feature should be optional but officially supported and not enabled by default to preserve A3 canon. This way, BIS can benefit from further sales of A2/OA/DLC once new customers to the series buy A3 after release; the community benefits from having a larger set of assets to play with.
Official support increases quality of such conversion and ensures nontechnical user multiplayer compatibility.