Simple strings 54321 00002 C major (capoed 2 = D major) 02020 G major - actually lacks a third 0x420 G major - for real 02420 G major - if you are good at such things 02023 G 7th xx203 F Major x520x F Major again x2223 D minor x2x23 D minor - Note, it is the same finger form as G7 xx423 B minor x0202 A Minor
Tarheel, Double C is not an open tuning. Knowing chords doesn't mean you'll play chords exclusively or that you'll rely on chords as a sole source for melody notes. Nor does it mean that you will ever strum a single chord. As for open strings, even if you were in an open tuning, as the melody progresses it will include many notes that clash badly with the open strings. If you play no notes but melody notes, this'll be fine. If you place any connective notes between the melody notes, you'll most likely want them to work with the melody notes, not against them. In double C, if you play the A note on the 2nd fret of the 2nd string and then a "ditty" on the 1st and 5th strings you'll want to fret the 1st string at the 3rd fret. With those two fretted strings, you're making an F chord. What would be some good reasons for NOT understanding chords?
Understanding chords,and being able to hear them change, will help you free yourself of relying on tabs, and learned arrangements of songs. Just being able to play chords behing a song you don't know will allow you to participate in jams. Whether you use them a lot or a little they are still a good tool to have. I agree with Chip: What valid reason is there to not want that knowledge? Paul