I think these are useful where you need something small and unsupported - as Gunbird suggested, for 6mm scale radar towers and such. Being hard styrene plastic, they are easier to glue as well.
For other modelling though, I probably would stick with aluminium car body mesh or plastic stitching mesh because it's cheaper and can be cut to more sizes.
Still a good find though - thanks for posting!
@ Mason:
You can still get plastic tea strainers.