Most modern cars run a coolant pressures between 110Kpa and 135Kpa. They don't suffer hoses blowing off, but have a good safety margin where boiling is a consideration.
Besides the OP was asking about a different tank. The FL offering is particularly poor and cracks readily. No pressure cap is going to work if the tank can't hold it. So yes a better alloy tank will solve a problem, even if the factory 16 Psi is used.
Yes true, for emission reduction purposes many, in particular petrol engines, run normally at or just above the boiling point of plain water. Correct proportion of coolant increases the boiling point on it's own, the cap increases it even further. If the tanks are suspect then by all means fit a different one, but as you say a cap above standard should not be needed. You only need someone with not much nous to read that a 20 Psi cap cures all, then fits one to his tired system to have a big problem waiting to happen.