Right now, yield on USD and some other major currencies does not matter, and we can get away with it for the other benefits of crypto, only because the external interest rate environment is extremely low due to financial repression. This is not a usual state of affairs economically.
Ultimately, users will need an equivalent of an at-call deposit market where they can deposit their currency to earn interest, and withdraw at their discretion to make transactions. Otherwise it will be a financial disadvantage to hold SmartCurrency for transactional purposes rather than holding the real currency, especially for currencies in higher interest rate regimes, or when financial repression is eventually terminated.
The bond market as proposed does not meet this particular need well because it forces the user to lock away their money. Although this might be a neat way to earn investment return, this takes SmartCurrency out of the transactional system, and disincentivises use for commerce.
If external interest rates are high enough, it is IMPLEMENTABLE to have an at-call deposit market that pays users a yield (although less a percentage to incentivise shorts), combined with the ability to convert to and from non-interest bearing SmartCurrency at will if desired. I have a design for this, although it is not feasible in 2.0 without added flexibility in the parameterisation (which I aim to write a more detailed post on, and possibly submit as a project proposal in 2.0). It is simply not true what many people say that yield cannot be implemented. It's only that the version of yield that was put in place was flawed and failed, leading to philosophical rejection of the idea.