Pfthb

I learned barre chords many years ago, when I was learning guitar. It seemed at the time there was no other option, or perhaps I never ran across other options.
Now that I have taken up my guitar again, I see power chords and "half" barre chords everywhere. Is it because full barre chords are difficult, or is there an advantage of those ones over full barre chords (besides simplicity)?

From my experience, half barre chord and simplified chord leave some of your fingers free and you will have flexibility to add some more harmony to the play. Beside, sometimes you don't want too much ringing note: maybe it will be too thick and noisy for your play, so you ignore some of them by play half barre/simplified chord. This is also an explanation for the use of power chord, when you play with distortion sound, the sound will be horrible if you play a chord with many notes are played at the same time

Of course, another reason is it is much more easier to get used to, compare to full barre one

You can strum 6-string chords, and this may often require a full barre. But, as you discover the possibilities of guitar playing, that's very likely what you'll do LEAST! Just as a pianist rarely plays 10 or 12-note chords, you'll play a variety of textures. No point in a full barre if you're only going to play 2 notes. It's not really about being 'easier'. Just about doing what the music requires.

Not really, the "power chord" is not there for simplicity (even though they do seem easy). They are somewhat harmonically ambiguous. In rock and more specifically metal, the 3rd and other tones add too much texture to the rhythm section. Sometimes the root motion can be intricate enough and playing the 5th and octave allows one to create a powerful sound using parallel harmony with tones that have common harmonics.

The 1 and 5 share many overtones that support each other and help create a resonance. This literally adds to the power of the acoustic signal. In some cases guitarists may play power chords out of laziness but they serve a purpose on modern music.

The half barre chord is used a lot in classical guitar along with open strings, either explicitly or via resonance, to create a full sound.

'Power chords' are easier to play, there's no doubt there! Especially when the bottom is tuned to D! But, they have become part of some styles of music, and actually need to be there for that reason.

Full barre chords? For many decades in bands I would pretty well always use them - depending on the make up of the rest of the band. However, on guitar there are many of the 'more advanced' chords that don't lend themselves to being played with all six strings. Mainly due to voicing and not being physically able to reach all the notes required.

Another good reason to only play three or four notes from certain chords is complementing the other players. The 'less is more' syndrome!

As already mentioned, playing with distortion means using fewer notes, as the harmonics highlighted by the distortion will only make big chords sound muddy.

If you are the only guy playing, and rhythm guitar is what's needed, why not play full barre chords if you can?