I never felt the whims were in any way a reflection of my sims's personality, but I turned them back on again in case I needed to farm satisfaction points now and then.
Ideally sims autonomy should reflect their traits while the whims should reflect their current emotional state. So instead of "flirty-> autonomously flirts undiscriminately with everyone around" sims under the overhauled system would go "flirty-> roll whim to flirt and roll whim to do flirty introduction to someone new".