I just created metadata simultaneously for some rasters. The were in a file workspace as opposed to a geodatabase workspace so I'm not sure if that will be an issue. If I understand correctly you are trying to create generic metadata for multiple files. Here's what I did:
Open arcCatalog and update the metadata for one of the files
Be generic so the text will apply to all files
Export the metadata into the same folder. (I have the ISO 19139 metadata implementation specification selected in my arcCatalog options).
The file will be exported as an .xml file.
Open the following tool: Conversion Tools>Metadata>Import Metadata... open it with a right click and choose "batch" (it's the one with the model builder symbol next to it)
Now you can add your exported metadata .xml file as the source and navigate to all the files to apply to as the target.
Granted it's a bit awkward to do this for large datasets (navigating to each file for example) but as this is a model you could easily modify it to work as a tool instead. Choose the recursive option and it will add all files within a folder to have the metadata attached. In fact, I might do that now and post it here.