The ESP Guitar Company

more diversity heavier riffs ballzier chords

More chord voicing options. It's silly to limit yourself. 

you can have a standard six pattern (eadgbe) but then drop the low 7th string (aeadgbe) allowing for full open chords and sick power chords and shredding

i love that seven string raw and heavy sound

Not a big fan of the 7 string.

More range for a vague reason. If you like heavier, down-tuned music, you can create it with a better voicing.

If you just wanna try it and don't like the extra string, you can set it up as a six string.

It's versatile - for demos and preproduction, I use my seven string for the bass track and can accomplish a good tone with guitar processors.

steve vai use it

Love 7 strings. Wish ESP would bring back the Ltd f 7 string or make an ax model 7 with a neck through body & EMGs

yep, Im on the 8 string kick now. You can go low and nasty but still play in standard. best of both worlds

Yes, more options for songwriting and interesting harmonys, plus it sounds brutal.

their fucking heavy

More options of sounds <3

I love 7 strings guitar! Good to make power riffs! \m/

In case of riffing 7 strings add the extra punch and tension. Besides while playing a clean arpeggio you get the plenty scope of utilizing a wide array of tonics in multiple octaves. :)

I voted yes but I have never owned one. Why not?

Not the best for all situations, but certainly a very useful tool of expression.  I would always have at least one 7 string on hand 

whenever possible.   

I find it has more clarity and attack that tuning down(and yes I have tried both).

I've started playing 7 string in 2004 and currently don't have any 6 string guitars at all.

Yes, because it provides more features without significant losses