It's not that hard really. The play has to pass some of the following categories. We could come up with a practical list which will be objective, I'll just have a go here:
1) Won titles at the club, with signifcant contribution.
2) Won individual awards or international cups and/or generally elevated the Inter brand name.
3) Scored a shit load of goals or was a top GK for many years, or generally was a top player for years while at Inter.
4) Been part of the team for 2 seasons or more (realistically it should be 5+ but it's harder these days)
5) Post-career has been promoting or supporting Inter. Or is also part of Inter Forever.
6) Did not show any affection - post-career mostly - to any of our direct rivals (Juventus or Milan, that is).
7)....
So if we figure out how many categories there, which, and how many a player has to check, we can have a relatively objective list. Nagatomo doesn't belong there regardless.
So from this category list we can argue that players like Maicon, Milito, Ronaldo and Vieri should all be part of a "Le Grande Inter" section. But since the name comes from a particular 60s team, it's unfair to use it. It was a name that was reserved for back-to-back European Cup winners. Maybe if the section is renamed, it'd be easier to come up with an objective name. I wouldn't say 'Hall of Fame' either, but something like Greatest Interisti.