It was important back then because it was one of the factors that lead to i13 PvP collapse and the PvP community for some reason believes we could stop i13 PvP changes from happening, but like you say in the grand scheme of things with the aftermath of i13 and its not most people, but everyone (overwhelming majority) from PvPers and PvEers would say how DR worked turned out to be completely unimportant overall after the issue went live.
I think players were generally very negative on DR even before knowing the mechanics of how it worked, because of the very obvious large-scale changes it made to how tactical builds functioned. Knowing the precise mechanics would have been useful if players were interested in working to tweak the existing system because making fine tweaks required really knowing how it worked. But as the majority of players discussing the changes wanted it removed entirely, knowing how it worked mechanically became less useful to know.
In particular, I felt it was important to know that the choice of Alpha and Beta (aka DiminishingA and DiminishingB) didn't just tune the system, it actually created totally different diminishing curves for different attributes. Some choices would create what I would call diminishing returns curves where higher incremental strength input created less incremental benefit, but there would always be an actual benefit. But others (like the original parameters for tohit, say) created what I would call asymptotic curves where no matter how much strength you put into the system you were basically hard-capped to a particular value. Knowing this, players could advocate for altering Alpha and Beta in ways that would create more reasonable diminishing curves, particularly when they affected related attributes (tohit and defense, say). But very few players were interested in exploring such changes.
Unfortunately, no matter how many times I offered this guidance it rarely impressed anyone: when you don't like something, advocate changing it in a way that eliminates the worst aspects of it while adding benefits it didn't have before that can compensate for the rest. Don't advocate ripping it out completely. The first is in the realm of the possible. The second is in the realm of tilting at windmills. True in general, particularly true for the Paragon team. Once your position becomes that you won't accept any solution that doesn't eliminate whole systems the devs have just released, you've lost.
You could kill a power or a power change or even a mission design in its crib. But an entire system? By the time a system reached us it was too late to advocate killing it entirely, at least not at its initial release. Systems took a long time, once created, to be demonstrated too problematic to fix. A canonical example would be how long Defiance 1.0 stuck around before being eliminated - by the devs themselves, not because of player-advocacy. It wasn't until analysis suggested it was
killing more players than it was helping that it was targeted for replacement.
The sad part about DR is that its effects on high-order PvP could have been essentially eliminated in two separate ways, but in the end no one capable of achieving either wanted to have anything to do with DR, or PvP at all.
