Sure. But if you cross the border (with agency) illegally, what else would you suggest?

For me, it depends on context. The consequence to both the person who crossed illegally and other people increases dramatically with the length of time that person has been here. Someone who crossed the border 20 minutes ago suffers modest consequences if they're turned around and marched back. Someone who crossed the border 20 years ago, who has married and has two children who are U.S. citizens and has built a life here? A lot more negative consequences, not only to them but also to innocent people. That stuff changes the cost-benefit analysis to enforcement decisions. It's why the immigration laws are larded up with humanitarian and other considerations.

There are plenty of countervailing principles that people of good conscience can - and do - raise against taking those things into account (or at least against giving them a lot of weight): moral hazard and negative incentives, for example. But regardless of where you land on it, we should acknowledge that there are some good-faith arguments against "it would be good policy if every single person here without authorization were to be deported without exception."