Normally, the whole idea of keeping a franchise name is because previous installments have been successful, either commercially or in ratings. Killzone (PS2), though, is widely seen as medicore at best, and Killzone: Liberation on PSP is not much better. Both did not sell spectatularly.
One of the main things you hear people saying when trying to refute Killzone 2 is "Killzone 1 sucked so Killzone 2 will as well" which, while of course it wont be that way, it doesnt create the best perception of the game among people who dont know a whole lot about it.
If it had of been a seemingly knew IP (same game different name) that was getting all these wonderful previews, it would have got a whole bunch more people jumpin around, gears-of-war-esque.
personally i can not see any advantage to keeping the name killzone, though maybe someone else can point one out to me.
Bet With routsounmanman: By the end of Q1 2008 Capcom WONT have announced a RE5 Wii Edition OR a new RE (classic gameplay) for the Wii (WON)







