I'd honestly prefer proximity xp/gold over the multiplier.
Back then, cmp was member of Mercenaries and just started to mod cRPG. Mercs had great influence on chadz and rest of the dev team. Back then, they were elite army and couldn't compare to big clans (Fallen, Templars, Shogunate). Dozen of them, no matter how skilled they were, didn't have much impact on final outcome. Especially when we all used to play on 200 man Pecores server because EU official servers were laggy mess.
I remember it very well, you could always hear (or read) one of them QQing how proximity is nonsense and how it takes skills away blah blah. They all hated Finn and his student, Finished (known as Michael).
Dev team (chadz) made the change but good portion of responsibility for that change goes to cRPG clan Mercenaries because they did everything they could to influence chadz to make that specific change.
Btw. Pecores stopped being active after that change.