From the link you provided:
In the coming months, this free playback streaming experience on Mixcloud will become slightly more limited. Itís important to us that, as a member of our community, you understand why.
The short answer is: so that we can keep up with the costs of running a streaming service that puts artists and creators at its core, and so we can build a sustainable platform that will be here for you in the long term.
Seems reasonable, I would guess running a streaming service is extremely expense, from the hosting and bandwidth costs, to website maintenance. The limits for the free streaming aren't that bad, tbh, and it seems like it is either this, or it will shut down at some point.