Yup that's the only reason I can see for them doing it. I've just noticed that if you disable 24-Hour Time in your Date & Time settings you get the am/pm suffix

Yup that's the only reason I can see for them doing it. I've just noticed that if you disable 24-Hour Time in your Date & Time settings you get the am/pm suffix back for the times but I think adding a ° symbol makes most sense.