Bonds have been hit by "kryptonite"
Bonds have been in a ‘non-traditional’ trading scenario for over 10 years now. As Central Banks around the world tried (try) to stimulate their respective economies they have ether lowered official interest rates or actually brought sovereign bond to push borrowing cost down. This has led to large capital appreciations in bond prices but has squeezed yields (which was the intended aim). This, as argued by Rabener, is leading to poorer returns for new and existing holders going forward.
However, we would point to asset allocation as a core part of any investor’s strategy and bonds (fixed interest) are a big part of asset allocations. We understand the current returns compared to historical returns are different and are likely to remain so in the medium term. But, chasing less liquid (e.g. unlisted infrastructure products) or high-risk yield products (e.g. Residential Mortgage Backed Securities) comes with its own risk too and are not necessarily fulfilling the fixed interest definition.
If we return to asset allocation idea, the returns you are eluding to are likely to come from risk assets such as equities and property, your fixed interest holding component is there to mitigate event and cyclical risk like we are experiencing now. Bonds and fixed income have never been and are not intended to be high returning assets.