The point is to give an area to play with resources, and people MAY challenge you (the wording of the dialog) to try to take the space for themselves.

What it is now is better worded as, "Claim this workshop, and other players WILL come and fight you, even though usually it's not because they want the workshop, but rather they just like the psychological outlet they need because of their frail egos. The good news is, usually these players only do it to low levels who are easily dominated, so if you are a high level, it's less common."

Bethesda, in their infinite wisdom and copious online gaming experience, didn't recognize how badly their game is imbalanced for PvP, and didn't realize that this workshop mechanic would result in a broken worshop in general, which facilitates small-ego'd players a method to help salve their small ego by griefing other players.