ElasticSearch or Redis seem like a good example of the challenges with that approach. Managing contracts is tedious and there's a substantial convenience factor for the difference between “click and it's running on your existing bill” and “go somewhere else, get setup with a license, take over O&M for your own servers”.
If it's really critical, you'll do that but a company has to be really dependent on a piece of software (or unusually cognizant of the open source maintainership problem) to go the second route. Built-in defaults carry a lot of weight.