This is a specious comparison. Obama was talking about the spike in unaccompanied minors in 2013-2014. I think there’s pretty broad agreement about that not being something to encourage.
The mainstream D approach to immigration during the Obama years was not something I really agreed with, but I understand the political calculus. They took a dual-track approach of trying to manage around the edges the humanitarian concerns and provide a modicum of fairness to Dreamers, et al, but also to take a hardline approach on deportations. This was done with an eye to building a bridge to Republicans on border security, so a comprehensive reform bill could get done. Now, is this criticizable from the left? Of course it is.
So, what happened? The comprehensive reform bill didn’t get done, because Freedom Caucus types didn’t want it done. So today’s status quo reflects that reality. It’s kinda like the shift to the left on health care in the D primary. Republicans are going to holler socialism no matter what, so you might as well stake out ground that’s popular with your primary voters. On immigration, Republicans aren’t going to do a deal with you, and they are going to say you favor open borders no matter what, so why not do what’s politically beneficial to you in this particular moment?
As for the last bit, why should it be an article of faith that crossing the border without approval should be a criminal offense? I’m not really sure what purpose that serves. Make it a civil offense, collect a fine. Give people who want to work the right to stay and work. Give people who aspire to citizenship, regardless of how they entered the country, a path to citizenship. Help stabilize the Central American countries to stem the humanitarian crises that are causing so many people to trek north. Don’t accept that you can either do nothing and expect things to improve, or unring a bell and fix the problem with walls and tough talk.