Vegans are not necessarily asking for anything. They will simply buy products that no harm was done to animals for, given the choice. As a result they will buy more of the non-animal derived products. Some plant-meat/dairy/egg may be on the menu for vegans, but that's not what defines them.
Sure some vegan may voice their believe that "all animals should be wild", but not even this belief is shared among all vegans and not all are activists.
Your statement "it's never enough for vegans" has two sides for me. If someone abstains from animal derived products, vegans will generally think that's "enough". The mission and "required behavioral change" is very commonly agreed on by vegans (contrary to other movements). On the other hand, most vegans are very aware that pest control is not going away soon, and that fast modes of transport will cause some (mostly bugs) collateral harm. From this point of view you are right: there will always be some next frontier of harm reduction. It will never be enough.
For me there is a line between breeding domesticated animals, and the regretted harm caused to wild animals. I find the first appalling, where the latter is something I cannot reasonably go completely without (bugs on my windshield, pest control, etc.).
