Hello Nikos
As far as I know, this is the only way to do that. Otherwise, you may create your own report using BAPIs BAPI_MATERIAL_MRP_LIST and BAPI_MATERIAL_STOCK_REQ_LIST.
Nevertheless, I think that you should test the business function activation. Besides the cross-plant view on MD04 there are other useful functionalities introduced by this business function and I can't remember of any negative effect of that. See the documentation below:
SAP Library - Production Planning and Control
BR
Caetano