Hi Soumya,
Regarding the use of MDG for a BOM scenario, please take a look at SAP Note 1703308. This note outlines the type of BOM usage for which MDG would be appropriate.
MDG is not designed to replace PLM in a customer's landscape and as you note, there are scenarios that are quite appropriate for PLM and MDG working alongside each other. This integration is essentially call(s) from PLM into MDG at the times in the PLM process where you need a material to be created. You would then call an MDG change request to create the material following your governance process. Perhaps initially this might be a "partially created" material and then later in the process, an update CR would be called to fully govern and create all of the views as needed. This integration is possible and could be implemented via an SAP consulting solution.
If you need more information on this, please let me know.
Best,
David