DC and DB plans

I believe there are 2 types of retirement plans offered in the U.S. currently, defined contribution plan and defined benefit plan. In the DC plan, employees make investment decisions and bear investment risk; in teh DB plan, employers make investment decisions and provide guarantee retirement outcome. The traditional method is the DB plan, but corporate actions are shying away from DB because of its negative impact on financial statment. The dominant retirement plans offered nowdays is the DC plan. I am not sure about the statistic, but I believe the target retirement accounts are widely offered in most DC plans.
The behavioral finance theory argued that average individual investor is not well suited to make retirement investment decision because most of the traditional finance theory assume average investor is ratioanl and utility maximizer. Bahavioral finance people argue that due to limited time and intelligence, average investor is emotional, use heristic other than statistic to make investment decisions. To be successful managing retirement account in the DC plan, an investor will need to have a good estimate of their retirement need, final salary level, life expectancy, and the various complex relationship between different investment vehicles. DB retirement plans are managed by professional managers and from traditional finance we know that they on average do not beat the passive index funds when management fee is taken into account. Such an complicated task is being handed over from the IM to the average investor and there is great risk that the majority investors do not know how to properly manage their own retirement account.
I once was scanning through a pension book written a Canidian author who serves in the pension industry. He argued that neither DB plan or DC plan is appropriate, that there should be a third, or maybe millions other version to the the simple approaches. So i was thinking that maybe one possible approach is to combine the DB and DC features in a new investment plan -- using the DB features to ensure minimum retirement amount is met and uses the DC features to allow flexible investment options once the minimum is ensured. But that's easier said than done, setting and achieiving the minimum income is already tough enough. Oh wait a minute, isn't that what we were asked to do in level 3 CFA exam, to design an investment policy statement for individual investor. Yes, i can do that, but the problem is how to turn custom tailor workshop into massive standard investment factory, where investors can pick and choose the proper investment group according to their own circumstances, what's more important is, how to design the filter/rules that are intuitive to average investors.