The problem is, you can come up with all the policies you want, you can publicize them constantly...
The problem is there is a large block of the electorate who are politically ignorant who will always be swayed by short soundbites. And more media attention will be dedicated to republican rhetoric than the media deserves.
I don't disagree, but the Dem's preferred course of action is usually to blame their own left flank.
There is a lot of squabbling between the far left and moderates during primaries. But at this point most of the criticism is aimed at Republicans and Manchin/Sinema.
What makes you think they don't? They certainly talked about policy during the last election (while at the same time the republicans were talking about "OMG! Biden is old! Laptop!") And since the election they have been promoting their infrastructure bill to their constituents.
Did they pass BBB? Eliminate student loan debt? .... Roll back Trump’s 2017 cuts to corporate tax rates?
You are right... they haven't passed many pieces of legislation that would otherwise be beneficial (both to the voters themselves, and to the fortunes of the Democrats... assuming of course they actually get credit for passing it.)
The problem is obstructionism from the republicans (and, to a lesser degree, Manchin/Sinema). Their ability to "get things done" is severely curtailed, not by people who have big ideas about what to do, but by a party that largely runs on culture wars. Kind of hard to pass anything in that environment. (And sadly they will be at a disadvantage for the foreseeable future, because of the amount of political power concentrated in rural, pro-republican areas. And no amount of "look at what we want to do" will help with that.)
Ban new oil and gas leases on federal lands and offshore waters?
This is one of the few things that the Biden administration could do, even with a obstructionist republicans in congress.
Would it be a good idea from an environmental standpoint? Maybe. Probably. But in a time of surging gas prices, taking actions that might be seen as further increasing prices might be harmful politically. (Even if those gas leases wouldn't result in new supplies for years, it would still be a bad image.)