There is a wing of the ethical-vegan community who disapprove of meat substitutes, arguing that we will never truly do justice to our animal brothers and sisters until we have lost the very appetite for their flesh. So, it is not just those who eat vegan out of health concerns, who are concerned about meat substitutes.
Whoa, I'm an ethical vegan and pretty steeped in theory, and I've never encountered this wing before. I doubt I'll agree with them, but I'd be curious to read if you have anything you can link or cite.