It is to some extent a symbolic gesture, but symbolic gestures have power in our world, especially when they are done by the powerful.
And of course ICE is part of the problem. Sure, the way they are regulated is also part of the problem, and that also needs to be changed, but the boots on the ground and their direct managers are not blameless. And they are likely to hold full responsibility for some of the horrendous acts being committed, not everything is commanded from on high. Not to mention the criminal negligence displayed in cases like losing track of people's children - that was not an order from somewhere, that is some bureaucrat who should be held personally accountable for failing to do their job right with catastrophic consequences.