This obviously makes sense. But it’s explicitly temporary. Real immigration reform must go through Congress, and it would be more systemic than the tweaking done throughout Trump’s admin, including this short-term halt.
An cynical interpretation is that borders are closing across the world anyway and international travel is screeching to a half, so this announcement doesn't amount to much besides populist theater.
More cynical still!—this formalization acts as a "reset" before the Kushner's immigration bill is launched if Trump wins a second term. That would be the same numbers (roughly 1 million) but with preference to skilled English speakers, who can better displace the middle class.
On the brighter side, I don't think the Corona crisis is going to end anytime soon, so I could imagine this executive order lasting a year. After the 2008 crash, illegal immigration greatly lessened and the legal immigration supply shrunk. Trump is following, not leading.
The fact is, mass immigration is a product of a "booming" economy—Trump made this quite explicit, talking about all the immigrants needed because, supposedly, companies were moving to the U.S.
The threat of a pandemic and the economic bust brings people down to earth—it makes them inherently more tribalist and nationalists, or you could just say, more realistic, sober, and inward-looking.
