[grzm]

I think the answer is mostly that Soylent is new and associated with the startup world.

- initially announced on a blog in 2013

- crowdfunded on Tilt, raising over $3M

- got funding from a16z

Due to that it's got a lot of cachet. Also, the idea of a meal replacement is more in line with life/body hacking.

Slimfast goes back to 1987 and is marketed as a diet and weight loss product. One could consider it more "old tech".

This is just my very fallible perception, and I don't intend any judgement on either.