First off, no.
This suggestion only consists of noob-safeties in NCR that would just make it more annoying for everyone else. You would just get rid of a skill that's always been part of Fallout games. Don't just say "I hate thieves!!! Delete them all!". Instead, try to think of a solution that would change how the skill works, not just get rid of it because you can't think of anyway to prevent someone from stealing from you (aka walking one hex away from them, staying alert).
Edit: Besides this, thievery is one of the most unproductive skills in the game, as you can get as much loot in 10 minutes fighting in encounters as you would in all day of trying to steal in NCR. Yet, people just don't get that, so they continue to fail to steal the 2 caps I have in my inventory.
The second suggestion would just make it annoying when players are using the tagging feature the right way, as in wanting 5+ other people to join their party to hunt. That, and a group wouldn't be able to run from an encounter together, because they would have to accept it before going, wasting precious seconds. A better solution would be to have some sort of tone or alert-message saying that "_____ has joined your party" without having you actually having to waste time to accept them.