Are there ways to estimate the value of development cards in Catan?
I'm not aware of any tables like what you're looking for, however many years ago I did read a Catan strategy article which gave the advice that you should treat every development card as a victory point. What the author meant was that generally they should be played in a way that immediately gains you points. For example, the Year of Plenty could get you the resources that allow you to surprise other players and build a settlement or the road building card might let you get to an important spot before another player to build a settlement before they can.
Overall I think you underestimate the power of the development cards, the year of plenty isn't simply trading the cost of the card for three new resources, you're getting three resources that can be called on at almost any time yet until you use the card they cannot be robbed and don't increase the size of your hand.