I don't have my Soylent yet, but the reasons I'll be doing it are definitely not hipster. Some reasons very similar to other comments in the thread, others might be unique.
Strong aversion to cooking and food preparation, and a general resentment of all the social baggage that goes along with procuring, preparing, and consuming food. Yeah, I've got issues.
I drink a lot of Ensure Plus these days. In the past it's been Carnation Instant Breakfast, Slimfast, Ovaltine, MetRx, various bodybuilding shakes, or whatever can of shake mix caught my eye at the health food store. When I was in high school, at lunchtime I would sometimes go buy a quart of milk and that would be lunch. Before the shakes it started with PowerBars when I was a teenager; then Clif Bars, I have basically lived off them at times. Or Luna Bars, or Balance Bars, or whatever.
Not like I've been solely surviving on fake food all this time, far from it. I eat sort of regular some of the time, get a lot of drive-through burgers, grill cheap cuts of beef, make spaghetti, but an awful lot of microwave meals and snack-food-as-meal type things too (e.g. Hot Pockets). And often I just eat mass quantities of dessert foods when I get hungry (Krispy Kremes FTW! I occasionally eat a dozen in one sitting).
Your friend's comment about not being cognizant of, and taking responsibility for, the physical realities of day-to-day living: Yeah, I want that. I don't enjoy thinking about food and my bodily functions and I want to put it all on autopilot as much as possible. Yet I still want to have good nutrition and not completely screw my body up. I'm in relatively good health now, but overweight and woefully out of shape. I sense that I'm pushing my luck (I'm age 41) and I won't stay healthy unless I regularize my nutrition.
I've had daydreams in the past of growing my own vegetables, having chickens, sheep, and a dairy cow (may do that yet), preparing nutritious whole food that I grew myself; but the stark reality is I HATE doing all that stuff. My mother-in-law gave me a dozen daffodil bulbs a couple years ago, and I resented every minute I was digging in the clayey, rocky spot I picked to plant them. I spent $50 on fish for the pond a couple years ago, must have been too cold when I put them in because I never saw them again after I dumped them in (granted, it was months before I checked on them). We planted fruit trees a couple years ago and unfortunately do zero maintenance to them; most of them are still alive but the bugs get at them pretty bad, and we missed an opportunity to prune them and train their branches and so on. Maybe through the miracle of nature they'll produce fruit one of these years anyway.
I recognize the magnificent value of being intimately involved in sourcing and preparing one's own food, but good grief it's like a whole career just doing that, even if you buy it at the grocery store. And you have to do it e-v-v-v-very day, three times or more a day, again and again and again and again...
So, yeah... Soylent. One of these months.