SoundCloud said that the move was to counter "an increasing number of applications that abuse content."
To be clear, this does not affect songs that are embedded and streamed directly from the SoundCloud app. The limit only affects its API.
Many developers who use the SoundCloud API are up in arms because they were only given 15 days notice, which they claim isn't enough to reprogram their app.
The service is facing increasing competition with Apple Music about to come online, and YouTube's Music Key waiting in the wings, so this isn't a great time to be upsetting anyone in its ecosystem.
You can read SoundCloud's announcement directly here.