Trust me having the correct WB whether shooting RAW or JPEG does MATTER. It's the difference between a person having the right color or them looking like an alien. Sure you can fix it in post, but it isnt always right.
I shoot about 20+ weddings a year and before I take any shot (especially when the main light source has changed) i re-do my WB.
For my work, I find that having the correct WB in camera yields much better photos. And it saves a ton of time when editing. When editing thousands of photos every week getting it right (WB) in camera is crucial.