Access to more information will help congress members write better legislation. It can also be used as a weapon against the enemies of the green new deal.
Here’s an example from last time.
https://thinkprogress.org/new-house-climate-committee-resembles-2007-panel-despite-12-years-worth-of-new-climate-science-fefbc29628ff/
I guess this time Democrats trust Trump’s EPA so they don’t need to subpoena anyone