I remember one idea coming from Dmcdevit, who proposed that for really obvious cases the ArbCom would simply hold a vote on the main RFAR page. How often does a chronic revert warrior get put in front of ArbCom, and you think "Revert parole for him, mate", and this is exactly what the ArbCom does - two months later? You could aid this process by requiring people to collect the majority of their evidence before requesting arbitration, as I did in my most recent case. This would significantly streamline the arbitration process without losing effectiveness and or adding bureaucracy.
That wouldn't allow the "defendant" a change to defend themselves fully.