I have given up on juicing much wheatgrass for now. Growing it is such a hassle - unless maybe one had a huge yard & lives in a climate where one can grow it year round.
As for other juicing, it can actually cause health problems if done excessively. I became hypothyroid after juicing a lot. Some things like spinach and brocolli are goitrogens - damage the thyroid - and juicing gives them in concentrated forms.
Mho we need more than raw fruits & veggies (though I don't think we need grains. I have had hardly any for months & that has caused me no problems). I think we need meat and eggs and yes even milk. I used to be vegetarian because I felt so sorry for animals with factory farming. But when I got sick and ate meat I would feel better! There are things in those protein foods that simply are not in veggies & fruits which is why people have to supolement things like Vit. B12 & carnitine. Maybe there are other things they have that we need that haven't quite been analyzed yet.
Some people do, indeed, live a long time on a vegetarian diet, but that doesn't mean it works for everyone else. Didn't work for me!