Barre chords are the same notes as open chords but sound 'fuller'.
Barre chords let you play sharps (and flats) with ease.
Barre chords allow you to make funky percussive shuffle beats.
Some songs that sound sorta wrong in open chords come alive with barres.
Once you get comfortable with barre chords try adding them to songs you've formerly played open. For instance an F to G change can become a barre move.
Electric guitar often uses barre chords and often varies open with barre shapes to give different texture to verse or chorus.
Don't look to clamp vice-like in a barre, try and flex dancer-like between positions. Remember an E to A move played with emphasis on the low strings will sound fine even if the E string sounds open as it's in key.
'The sound of the city seems to disappear'