Is it plausible to depict the Segmentata using armor upgrades?

[Ludens]

However, I thought that Trajan's column basically give us the impression that the Segmentata is a ideal armour that Romans wore? That is represent the ideal armour for the Roman army?

Ideal? Not necessarily. Presumably, the artist used LS to better distinguish the legionaries from the auxiliaries. On the Adamclissi Meteopes, which celebrate the same campaign, many legionaries also use chain mail.

Thanks for the answers, PVC and ljperreira.