If you’re going someplace cold you’ll want warm clothing and if it’s sunny then sunblock is a big deal, but in general you don’t need much stuff on a trip.
My guess is you're not hiking for 10 miles in possibly chilly rain in England or wherever. (Or needing a shell because of wind.) An umbrella doesn't really work and you're probably not wanting to just walk all day drenched. In a city, yes, umbrellas are often a reasonable alternative.
If you’re going someplace cold you’ll want warm clothing and if it’s sunny then sunblock is a big deal, but in general you don’t need much stuff on a trip.