Cool. There are some guitarists that use more complex chords. Alot of Jazz and Blues players will utilize 11th, dominant b9, and 13th chords. I think it has alot to do with the sound you have, a piano is purely acoustical so complex chord structures sound good. Play a dominant 13th chord on a heavy distorted guitar and (frankly) it sounds like crap. If you play the same chord on a acoustic or a clean guitar, it doesn't sound as discordant. You can get a nice sound with some chords on a lightly driven guitar (bluesy and maybe alittle heavier). A cool trick though to get some more complex chords to sound decent on a heavy distorted guitar is to ommit a note from the chord. Like the power-chord, you ommit the 3rd. Apply the same rule and ommit the 5th from more complex chords like dominant 7th's, and such. So a A dominant 7th would be 5x56xx. Makes a much better sound, because the 5th is just there to enhance the root basically.

Try taking out the 5th in major and minor chords like 7th, 6th, and 9th's. And take out the 3rd in diminished and augmented chords, if needed. It will make a less acceptable chord more acceptable.