Carmine has the right idea but I'll detail it a bit more :)
Chords are like words. Obviously words comes from letters. In the same way, chords are an arrangement of different notes from a given scale.
Do you know every words from the english dictionnary ?
I don't. Do we need too ? Not really unless your a writer and you want to be able to express yourself in different ways depending on the mood.
If you like to and can express yourself with only open chords, you dont need to learn other stuff. I think we shouldnt stress ourselves with this. Wanting to learn new chords will come on its own someday just because we will want to express ourselves differently.
As for learning the fretboard. I think it's very important if you are into writing melodies and even more if you are into improvising . If I ask you to write a word, well you write it down without much thinking, its natural. That's what you want to be able to do when improvising. No barriers between what you feel and what you play. To achieve that, you need to know your "alphabet" and a bit of grammar (fretboard and scales) :p
I think there's a tendency lately to learn everything we can learn in music because we think it will make us better musicians. That's so wrong. That makes us more an encyclopedia then a good book. Music is simple. Expressing ourselves with what we know, that's all.