I dont think there is anything wrong with them taking these things. I do know of some fellow FA's of mine that dont like the pax taking the safety demo cards, but I dont see the big deal. Its not like there is classified info on those things. On USAirways we have the Attache magazines that we encourage the pax to take with them anyway.
Why not what is the worst that they could do with them? Read the or pitch them... Barf bags I question as to why someone would want that??? As for the saftey cards and inflight magazines. Sure,if they are content with that why not. Cutomer satisfation....LOL