Because a straight shot from the Gamma side of the Wormhole, would take you through Galactic center, so, you have the extra distance going around Galactic Center, you don't have that issue with Kazon Territory, because you're already on the outer edge.
Doesn't work that way. Earth sits basically on the border between Alpha and Beta (Trek fact) halfway between core and rim (real word fact) so a clear line of sight past the core would mean going about 20 degrees off the axis connecting Earth to the Core. Or, in other words, 20 degrees off the galaxy-dividing line that is the Alpha/Beta border as well as the Delta/Gamma border.
Both the starting point next to the Ocampa planet and the far end of the Gamma wormhole meet the specs. At least according to the onscreen map. Indeed, the Gamma wormhole end meets the specs better!
You don't have to imagine a 10 thousand light years out from the centre of the universe impenetrable fence, that everyone has to go the long way around, because it's there.
Or then there's this teensy weensy energy cloud fairly close to Earth, right between the human homeworld and the galactic core, and no one has bothered to take the long route around it before the late 2280s. After that date, of course, everybody starts taking the scenic shortcut right through the color show, as they learn there's nothing impenetrable about the Barrier after all.