Yes, Gambler’s Fallacy and other sources of flat, base, crit-rate would need adjusted (possibly to a fixed guaranteed critical hit at top of current range-band system, but I’m not balancing anything from a forum post) - you’re correct there. Simplifying the overall system doesn’t mean we haven’t created a problem for ourselves already.
Singularity actually highlights the problems we have with the current structure. We give up all Base Critical Hit Rate (which sometimes is mandatory or incidental while fleshing out a build) to get a Flat bonus Multiplier. When a player can add to an axis but get no return, they’re less likely to make that trade - it doesn’t matter which direction it works in. Any method of disabling an axis has to involve a scaling method of adding to another - otherwise players will feel cheated (and probably will be).
So, the question is, if you got more base damage, or more increased damage from using Singularity, proportional to the crit-chance you gave up, would you still feel like Critical Vulnerability was too big a problem? I don’t think so, because then all damage is accounted for in every action - just the methodology changes. Min-Max players are going to min-max with whatever methodology is best, right now, Crit is the easiest one to use, because it’s a scaling more-damage multiplier that can be added to an otherwise punchy build with little opportunity cost.