Honestly, I used to think you had to brown meat first for a good slow cooker stew. My last two pots proved me wrong. | Easy Slow Cooker Meals - Librear
Browning adds a deeper flavor you just can't get without that sear. The Maillard reaction creates complex tastes that slow cooking alone misses. My stews always taste richer when I take those extra ten minutes.
Is there any other way to make stew? @hunt.kevin is right, skipping the browning step is just lazy cooking. You end up with boiled meat soup instead of something with real flavor.