Not putting solid food into your system for long periods of time (months, years) will destroy your ability to digest solid food when you start refeeding. I've seen people in eating disorder facilities who have lived on diets of liquid food (historically Ensure, basically the same thing) who have not defecated for months, and when they start eating again suffer for weeks and weeks from horrendous constipation, often r…
When you consume liquid calories, you miss out on this important part of the digestive process (and subsequently lose out on absorbing a portion of the nutrients), unless you are "simulate chewing" or leave the liquids in your mouth long enough for the salivary enzymes to "get to work."
Granted, this doesn't mean you can't survive off of liquid calories, but digestive issues are bound to happen. Nutrient-dense, whole foods should always be the first option.