For an explanation of my position and reasoning, please just see what I wrote to Sony:
I am a fan of the Rock Band video game and am wondering why the Rock Band Network DLC releases are limited to only five per week for the PS3. It makes purchasing the game for the Xbox 360 seem much more attractive for new buyers, and even for existing players it seems attractive to switch.TL;DR: We aren't getting more official songs than before, but we're still limited to the same # of RBN songs. The limit should be increased to compensate for the decrease in official DLC, otherwise new and existing players will prefer the Xbox to the PS3.
Recently, Harmonix has only been releasing 3-4 songs per week as non-RBN DLC, compared to when the RBN launched when they released 6+ songs per week, with many weeks reaching 10 or more. The amount of RBN songs Sony allows seems to be unchanged, however. If there needs to be a limit, could it be something like fifteen total (between official and RBN releases), rather than artificially limiting the amount of content available players?
As I said before, the limited RBN releases make playing Rock Band on the Xbox a much better option for players who have both consoles or for whom money isn't an issue. There are certainly many RBN songs which I would buy, but they aren't available because only five songs are released per week.
So, let's try to create enough noise that at least the customer service people take note of the trend and possibly mention something to their superiors! It is easy to submit a question, without even needing to login, at http://us.playstation.com/support/ask/. Messages probably shouldn't be copy-pasted; write your own letter, even if it is just a few sentences.
Xbox/Wii players: We want your support too! Expanding RBN on the PS3 will help to improve the Rock Band community as a whole. Please take a couple of minutes to try help!