There are 2 separate topics that seem to get bundled together a lot.

1. Should we deport illegal immigrants? While there are some debate here (sanctuary cities, immigration reform etc), it's not the primary cause of the current ICE repulsion.

2. How deportations are done currently. Mass round ups, targeting everyone, including those with no criminal record, the violence involved. This is what most people are against.

Our immigration system is broken. Reagan realized this in the 1980s and gave amnesty to millions and Republicans were going to reform it. But businesses being able to abuse an unprotected 'undocumented class' won out instead.

> If all of the undocumented people in the US spent this much time trying to emigrate legally

Many of the "undocumented people" (what an Orwellian phrase) that have been rounded up by ICE are picked up during court hearings or immigration interviews. An easy way for agents to meet their quota without doing any actual investigative work. Say what you will about them but there's no denying those people were by definition "trying to emigrate legally." This has been widely reported.

Most illegal immigrants could spend the rest of their lives trying to immigrate legally and never make it, so that doesn't seem rational. Being undocumented is their best bet, as long as they don't break the criminal law once they're past the border and they make it 100 miles past the border their odds of being caught are next to nil. ICE is mostly catching people that either turn up in the legal system or are documented somewhere where they can be found.

As someone who immigrated here, legally, from a low-risk country, I can tell you it cost the best part of $35,000 going through the process, and byzantine weirdnesses and requirements that included things like my mother-in-law signing surety on my usage of Social Security and Medicare and other financial commitments because US immigration is in some ways so broken that it cannot at all comprehend a world where the immigrant might be the breadwinner, and not the USC (I was working as an experienced senior IT person while my US partner was back in college).

Ultimately, it would have been quicker, easier, and cheaper (and in the end, just as legal as my immigration) to come here on a tourist visa or the VWP, marry her in spite of the prohibition thereon, and ask for forgiveness and apply to be able to stay anyway.

When it's those three things versus "legal immigration", and other factors, I rather empathize with many of those people.

And as for your comment, it's more and more apparent that Trump intends for ICE to be his cudgel for all manner of opposition, not just immigration issues (witness the attempts to extort Minnesota into handing over state voter rolls, "We will move ICE enforcement out of the state if you do") so no, we'd still be having it.

ICE has been regularly picking people up at their asylum hearings and deporting them. That is precisely people trying to emigrate legally.