It really depends on the outfit/aesthetic. Some outfits are very much ruined by a belt and others will look very “weird” if you aren’t wearing one.

Everyone’s different, but I find that cargo pants and shorts look very much “I used to wear my phone on my belt” if you wear a belt. But jeans, slacks, and outright suits look REALLY weird if you don’t have that bar of color dividing pants and shirt.

Although, if you are wearing a more “outdoorsy” outfit (e.g. you shop at REI) then I find the belt very much becomes essential for aesthetics again.