Look at it this way. Pensions are annuities administrated by many of the same financial institutions selling annuities to the public. Current annuities are paying relatively little by historical standards, and are certainly NOT priced using 25-yr ave historical bond interest rates. If you were w#rking decades for a company offering DB pension, would you want your DB pension to be seriously underfunded by reasonable accounting standards? Would you want a company to promise you a significant benefit (e.g. pension) there was real risk it could not deliver when the time came to collect?
And while you and I may not see 30yr bond interest rates holding at (or below) 2.8%, the buyers of today's 30yr bonds obviously disagree.