personally i don't like prohibitive rules. i'd like to come at it with an attitude of "let's do this thing" rather than "let's NOT do this thing". in general i feel it leads to more creativity and less punishment. it also depends on whether you want your rules followed or not.
so for example restating rule 1 as: "players should make their best attempt to stay within biomes of bosses they have defeated or are working to defeat" or something to that effect. i could abide by that. but if you told me i'm 'not allowed' in the plains until later, i'm going to do everything in my power to get there sooner. and for some ppl that sort of rebellion may not even be consciously set out upon.