Regardless of what license the project is filed under, as an individual contributor working for free for the community, the license of a project determines the

Regardless of what license the project is filed under, as an individual contributor working for free for the community, the license of a project determines the terms under which I am sharing my work. I expect those to be respected in perpetuity, and I would like the right to rescind my contribution if the copyright holder is in violation of the license. The CLA is just another license to consider with the project; just like projects that have the "any later version" GPL clause. That little addition is important to some individuals. I think a more successful argument would be against the lack of specific guarantees in existing CLAs, rather than CLAs themselves. For example, the CLA could give joint copyright to the involved parties, but also agree to only publish the code under a license published by the Free Software Foundation. CLAs, as you point out, are sometimes a necessary mechanism to ensure that a project can correct licensing issues when they arise. Obviously, through careful choice of licensing it may be possible to avoid the need for a CLA entirely, such as is starting to be done with the Apache License 2.0 by some projects. So I would think of this differently: depending on the license, some projects may need a CLA for protections only available to them with one. For those projects, the community should encourage them to encode their intentions in the CLA to assuage fears and provide certain guarantees to contributors. Finally, keep in mind that the entire world does not follow US Contract / Copyright law (or even the bern conventions). In some countries, a CLA may be the only possible way to ensure that a project won't have problems later. While the current versions of today's "free software" licenses have generally tried to account for that, legal situations change over time.