Truss roof......why so many braces?

They certainly look like "wind braces" which keep your truss from folding flat like dominoes when pushed.

Without seeing the erection drawings for your roof, I can say that for my truss roof there were both longitudinal and diagonal braces specified as part of the erection drawing for the trusses. Trusses have a lot of stability in the direction of the truss, and none (of themselves) across the trusses. That has to be built in.

Trusses tend to lay over on their sides when loaded. In order to keep them in the perfect upright position, they provide 2x4 braces to keep the trusses exactly vertical.

In addition, some of the diagonal chords are in compression and will buckle if not braced to keep them straight.

I wouldn’t remove any braces until the truss manufacturer can verify it’s okay.