The Apache Mesos product adds business value. An incredible amount of it. But the source of that value isn't what most people think. Most think that the business value is simplification of deployment for developers so that they spend more time developing features instead of worrying about the deployment infrastructure. There is value for developers, but there's more.
Mesos eliminates cloud vendor lock in. Mesos slaves run on virtual machines with prerequisite software on it. Those slaves can exist just as easily on Amazon AWS or Google Cloud, Microsoft Azure, or any other cloud vendor. All cloud vendors provide VPN capability so that hybrid cloud (a mixture of cloud and on premise) infrastructures are possible; everyone wants that. You can't exist in today's marketplace without it. There's nothing getting in the way of Mesos masters running slaves in on premise our cloud infrastructures in any combination. Somebody makes a financial decision add to where slaves (or Mesos masters, for that matter) are hosted.
Mesos reduces switching costs between cloud vendors. One of the cloud "fears" I hear from clients is vendor lock-in. That is, they start with a cloud vendor, that vendor changes its pricing structure or the quality isn't what they need, then they have a large project to switch cloud vendors. Mesos makes switching cloud vendors or using multiple cloud vendors much cheaper and easier. Adopting a new cloud vendor consists of establishing a VPN and creating Mesos slaves in your newly consumed cloud. Through the VPN, those newly created slaves can communicate with their Mesos masters wherever they are hosted. From a business perspective, this feature eliminates business risk. Your application runtime environment is effectively decoupled from your cloud vendor.
Mesos vendor agnostic platform introduces a least common denominator problem. One of the advantages of using the cloud is to capitalize on cloud vendor R&D, which is much larger and often much more focused than what enterprises can do individually. Cloud R&D is realized by features such as dynamic scaling, which automatically scales your deployment to match the load it's currently servicing. The web is repleat with postings about difficulties in making Mesos dynamically scalable and utilizing other cloud features. Cloud vendor features will always be ahead of Mesos' ability to utilize them and will always have features that those adopting Mesos won't easily be able to use.
It should be noted that Mesos is popular enough to get the attention of cloud vendors. For instance, AWS is devoting time and energy into providing a way to dynamically scale Mesos slaves through the ECS Scheduler Driver. Azure and Microsoft have an effort going to bring Mesos (and Docker) to the windows world (here). A quick google search reveals that there are many other Mesos integration efforts with cloud vendors and there's every reason to expect this to continue.