Nowadays more and more companies are becoming environmental conscious and try to reduce their carbon footprint.
I would suggest to give customers the option to run the mendix server on renewable energy satisfying the need of those companies.
Although it would cause a (relatively small) increase in costs for running mendix (when this ‘green’ option selected),
companies would be able to advertise this as an illustriation for their concern for the environment. Moreover, it would also be a step closer to the goals of the Paris agreement to have a carbon emmission free economy in 2050.
Also, you can always run it in a datacenter of your choice by hosting "on premise”.
As far as I know, the Mendix Cloud runs on AWS. AWS doesn’t seem to offer a direct option to choose whether you run on green servers or regular servers. They do seem to have a serious sustainability program. According to their site, AWS exceeded 50% renewable energy usage for 2018.