Because, if there is equal chance of "winning" youll have one group that PvE all day long there, and random PvPers that doesnt find any PvP there. By making it a risk/reward system, you promote PvP, while making it "useable" for the PvE crowd.
Fed 1 : Stop ganking me, Im here for the PvE
KDF 1: This a PvP zone, cant deal with it, dont enter!
Instead it would work like this:
Fed 1: Stop ganking me, Im here for PvE.
KDF 1: Then disable PvP, you can still complete missions, grind loot.
Yes, but you are working with a premise that "ganking" is a bad thing. It's not. Some people like it. STO at this moment has only one place where you can do that: Kerrat. You can go for pure pve anywhere else. You can go arenas and CTF's for pure pvp.