So you're saying you shouldn't gain a big advantage for being a powerful guild? That would reduce, not promote competition.
I think you're missing the point. Big, powerful guilds will still be rewarded in the new system, perhaps even more than they were before because now, the goal will be to take and hold as many castles as possible each WoE. If your big guild can successfully hold 5-6 castles each WoE (woe1), you're going to have a HUGE advantage over every other guild. I'm sure there are many of the large guilds that could take more castles than that, but don't currently because most of their focus is spent keeping one specific castle from breaking.
As for the castle loots. Yeah, I think they definitely need an update. The current loot is pretty worthless and I imagine gets sold to the NPC rather than vended.