It's actually quite simple.
20% has always been very high, but it has helped to collect HBD to generate something like a stablecoin. Why this is wanted, please google it.
Only now, after Hive has fallen by almost half and is in danger of slipping further and further and fading from attention, this rate cut is an indication that you should rather exchange your HBD for HivePower, earn about 10-15% with posting and curating and also hope that the price will rise again. Then you can switch back to HBD with perhaps 20% interest again and have made a profit.
Have a great sunday.