I've never understood why landlords do this; presumably there is benefit they get from letting these storefronts sit empty than from lowering the rent to at least get something, but I'm not sure what it is (maybe a tax loss thing?). Seems like something the city should take action to combat.
Let's assume that there are actually retail tenants who would be willing to lease space downtown right now. And that's a big assumption, because the office foot traffic that supported the renaissance of a lot of the nicer retailers who came to downtown 7-10 years ago has dried up, the homeless problem is significant, and the crime is crazy.
But let's just assume for the sake of argument that there was actually some interest from tenants. "Credit" tenants---the national/regional retailers that owners of Class A office want as ground floor tenants---demand that the landlord invest a certain amount of tenant improvement dollars/abated rent in order to support the tenant's buildout of the space. Typically the more term the tenant is willing to commit to, the higher the TI dollars. Office owners who are sucking wind on the office tenants whose revenue is supposed to constitute 90% of the buildings' revenues do not have the available cash to offer much in the way of tenant improvement allowance to the credit retailers. That means that the only tenants who are going to be willing to take the space "as is" and make minimal improvements are mom and pops with marginal credit, so they are higher risk. In addition, the office owner (and, more importantly, the office buliding owner's lender) are not willing to "firesale" the ground floor retail to some pot dispensary, dollar general, second hand clothing store, etc. because then you are diminishing the quality of the building and its appeal to office tenants. No one wants to be first to go down that path, because the marginal increase in revenue isn't worth the impact of junking up the entrance to your building for the next 10 years and driving away the few office tenants that everyone is competing over.
But this will change gradually as the office buildings continue their steady march downhill --but for the Class A office that delivered in Penn Quarter/Chinatown over the last 15 years, that will be a slow decline.
I remember what the unrenovated older office buildings along 14th and 15th were like in the 90s---there were plenty of cut-rate retail mom & pops there then. Anyone remember "The Bikini Shop"?