Well, this is about 4000 years before episode 1, so maybe things changed since then, like strong weave or something. Plus, in the original trilogy there were precious few Jedi around plus they were forced underground, so I doubt they had the resources to make armoured suits.
The empire did, as seen with Vader, and some other Sith did wear armour according to extra lore and novels. But also it is just a matter of opinion of the person needing to gear themselves.
Anyways, interesting observation to bring up