I feel like you're just hand-waving away the issue. If they could move them out of the ICU they would have, the issue is they require constant care while on the ECMO machine.
Additionally, while the "smaller, cheaper, no care required" devices may appear in the future (the article talks about this very thing), they're not here _right now_. There's currently a limited number of machines and people who can maintain them in the hospital, and hence an immediate problem that they have to deal with when there's more people who can benefit from them than machines they have.