Elsewhere (HERE in fact), a debate was kicked off by Tim Carter regarding IP ownership, company ownership, free agency and a whole bunch of bits and pieces. So, elaborating on the answers here rather than chewing up and derailing the other posting...
You pointed out that "I" don't own the IP to Red Orchestra and Killing Floor. Correct. "I" don't own the IP, the company does. "I" just own a chunk of the company. And, before you ask the details, I was one of the original 4 owners.
We are independent, own 100% of the company and are completely self-funded. We have done a lot of work in the last couple of years on the investment market, but ended up deciding to do it for ourselves, without any outside investment.
We aren't glued to one IP. We make more. We own the company, we create whatever IP we wish.
We aren't "stuck" making sequels. We can chose to make them, or sub the work out. Or not bother. Or make something else. Or all of the above. Completely our choice.
We make money from selling units AND other exploitation of the IP. This is also why we recently decided to self-publish in North America and have since started publishing third-party titles.
So, lets see... we do everything you suggest we should like to do - AND own the IP - AND are self-funded, so are fully self-deterministic. So why would I want to be a "free agent"? We own our own company instead. And we develop our company brand - that is why we set it up. Besides, you are busy helping me develop my personal brand right here - so come along to GDC and help me develop it a bit further :)
I'm really not sure where this concept of "getting stuck married to your IP" comes from. We have succesful IP that we exploit. We do other things as well. We have other (new) IP in the pipeline. All our choice. No-one but us decides what we make. The idea of handing off all responsibility (fiscal and otherwise) for your IP and expecting to make a lot of money off it, unless your name is JK Rowling or Steven Spielberg, is a tad hopeful.
If you sell off the IP, yes, you may be able to do a deal for some residuals and other junk (not sure I've ever heard of such a deal in this industry, but who knows?). But you'll be lucky to see single-figure percentages off the net revenue from a publisher that way. We get 100% of the publisher's net revenue - we ARE the publisher.
So, is owning the IP a "burden"? No, not to us. It guarantees our future and our complete freedom to make choices, including deciding what we make next. Our choice on that one - Red Orchestra: Heroes of Stalingrad. Sorry, but we actually ENJOY it. We make games we enjoy playing. Fortunately, so do a bunch of other people, too (see "Analysis: On Red Orchestra, and Flowers")!