Mostly because it didn't even survive the Crisis of the Third Century :) Segmentata was expensive, high-maintenance equipment that was only used during a relatively tiny part of Rome's extensive history, starting at about 9 CE (Our earliest find) to somewhere at the beginning of the Third Century.

The design itself was rather complex and difficult to make, which already limited the ease of not only creation, but also repair. The bronze fittings were known for falling off very easily (They're relatively common finds from this period) and corroding the iron (because chemistry).

Chain mail, or lorica hamata, was regularly used through this period as well, and remained in use afterwards. Not only did it not require as much extensive maintenance, but the armour required much less skill to create, which allowed it to be produced far more cheaply and easily. Chain is also extremely effective at, y'know, keeping people alive, which is why it was one of the most popular forms of armour ever used (And why it's still used today for things like food safety).

TL;DR: Expense and maintenance made the armour suboptimal, even if it really does look fantastic.