It's nice to pick up all the vendor codes (weapon repair kits, rad-x, buffout, mentats, radaway), but I just like exploring in general anyway. It's fun to try once in awhile to get the sense that you're really nailing the survival horror experience, especially if you have good lockpick and science for access to everything.
Still, don't bother if you've found the beginnings of the DLC a chore enough already as finding inconsequential items will likely not feel rewarding to you anyway.