Most Americans get plenty of protein. Actually, most americans get too much protein. It can be hard on your kidneys.
As for your question, plant-source proteins are better for you and easier for your body to process than animal-based proteins, not to mention that you're going to be getting a lot of other vitamins, minerals and substances like isoflavones if you get your protein from the plant kingdom.
I don't want to start a flame war or anything, but from what I've learned while researching food and diet, meat(mainly talking about pork and beef, but chicken isn't that much better) isn't really actually very good for you. Especially with all the hormones and antibiotics they pump the poor animals full of. It's just not a good deal. Meat has a lot of calories, fat, protein, iron and that's about it.
Cooked food is dead food and dead food isn't good for you. That's basically what it boils down to. You can't go to a place like GNC and expect to fulfull your dietary needs. Maybe in another 50 years, but not right now. Don't you think your body can tell the difference between megadoses of synthetic vitamins, and the real thing? There are over 600 known compounds in an orange. Are you going to try and pop 600 pills, or just eat the orange? 🙂
If you really want to try and better yourself, forget about the protein shake and eat a kiwi. 😀