One of the main use case that is the product review session or any other custom application you created to analyse, view or share a model.
Until now you would have to export your model, load it in editor and then re-build your application or create a DLC for every model you want to see in application.
Now you have the possibility to try to load it directly.
Regarding the export failing:
- it should not be a size limit, maybe more a bad node or something in the model that fails on export and that you removed when you start exporting subsets of the model.
- did you check the Rhino console to see if there is any helpful error message from the exporter?
- if it is a model you can share with us we could have a look. Contact me privately so we can set up a box link to upload a model if that is an option.