Well, the Linux Kernel's position is that we want the contributions from companies like Tivo, because even though a particular device might be locked down. Contributions from companies like Tivo, and Sony, and Samsung, which may have some of their products with locked down devices, are nevertheless valid contributions which will help make the Linux kernel better --- and those contributions can also be used in completely free systems.
So it's basically a "stone soup" model, as it applies to developers. If you use my source code, you can use it for whatever you want, so long as my freedoms to get back your changes (which then I can use in whatever way I want, including in locked down devices) can go into the project.
As far as I am concerned, a locked-down device is a business model choice. It allows hardware to be sold for much less money, because it allows for alternate monetization strategies (i.e., the Tivo subscription services, video rentals, etc.) People who want to buy general purpose computers can always install the Open Source software on a machine of their choosing, and that's also fine. Whether you want to pay $199 or $699 and perhaps give up some freedoms as far as that particular device is concerned is also a choice which each user should be allowed to make on their own. After all, the freedom to choose is also a freedom.
Now, there are two counter-arguments to this perspective. Once is in a device with a mixed set of proprietary and free/open source software, it may not be possible to use the proprietary software on a general purpose computer. There the question is whether free software should be used as a bludgeon to force vendors of products which also use some proprietary code to give more freedoms to users (which may undermine certain business models as described above).
The second pontential argument is "what if there are no more general purpose computers". And there this is where the UEFI secure boot discussions become especially interesting. However, so long as it's possible to disable secure boot, or the hardware allows users to install signing keys of their own choosing, the threat of not being able to purchase general purpose computers where you can install software of your choice is not credible at least in the near term, and so long as we work hard to make sure it doesn't appear, I don't think will be a huge threat in the long term. You may not be able to get a general purpose computer with a quad-core CPU, 16 gigs of memory, etc., for $29.95 plus a two year subscription, but if you are willing to pay the full fair price, I'm fairly confident the threat of not being able to buy a general purpose computer is not a high probability outcome.
So the bottom line is we want developers to be able to be free to pursue business models that in turn allow users to be able to purchase devices that may not offer them the full set of freedomes --- but it's the user's choice that they get those locked-down devices. The FSF position is that they don't want their source code to ever be used in devices that might not allow users the full range of freedoms, even if it hurts the software project by turning away developers who have these business models that they disagree with.