This may need the data grid. But many use cases may reveal a real need for one. Archives do not have guaranteed long-term funding. ESA archives ditto. Publishers of electronic journal don't want long-term maintence load of their archives.
Data are fragile.
It would be bad to let single institutions to define their own metadata. Talks between data centres are more important than community consultation. BUT commnity input is also important to define requirements. That may mean at data source, not at data centre.