Well the one good thing about that fee (my cable company Mediacom charges it also) is that you know exactly how much you are paying for those OTA channels. I think Directv would be smart to break that out - lower the package pricing by $15/month for new customers and add it back via that fee.
At least as long as they were honest in their advertising and showed the full cost including all the fees instead of using the low package pricing to entice customers like cable does. I know, I know, nobody is but I think maybe that new law requires them to be more transparent in their advertising. We'll have to see how that works in practice or if they'll find a way around it.
The other benefit, other than letting people know how much they are paying for locals, is that a lot of the yearly price increases come from it. It doubled from a little over $7 to just under $15 for me with Mediacom in only two years. The price of my package only went up by $2 during that time. Directv wouldn't have to increase prices by as much if most of the increase was in the locals fee and RSN fee - letting customers know where those increases are coming from. Just like RSNs, there are probably some differences between markets in how much locals actually cost, depending on contract cycles etc.
It would also make it easier for them to allow customers to drop locals (if they ever get their act together with the LCC) by showing them how much they will save - and knowing that savings will only increase in the future.