Yup, Goodsprings is surrounded by gentle hills and low, easy to climb mountains, between which lie paths overrun by Giant Radscorps, Cazadores, and Deathclaws.
My first impulse was to take the easy route over a mountain between said paths, but I bonked into an invisible wall.
When you start out in Goodsprings, the game offers you a choice:
Head North towards Vegas and get eaten alive by Cazadores.
Head Northeast towards ... That place I forget, and get eaten by Deathclaws.
Head West towards mountains (and presumably a large portion of the map) and ... run into nothing. That area is completely unused and blocked off.
Head West and get eaten alive by Giant Radscorps...
Oooooor, head south on the cozy path populated by Coyote Pups and Bloatflies towards Primm.. where you're SUPPOSED to go.
It isn't impossible to go in a direction other than south from Goodsprings, I've done it before.
But the game tries its darnest to herd you in the direction it wants you to go and to constantly remind you that you, in fact, are not the master of your own destiny. It is.