Oh, absolutely. Honestly, in the absence of better analysis tools, I think ablatives are the best current option, as they can handle much higher heat loads with much less cost and fragility than the reusable options. None of the current methods are what I would describe as great though.Fair enough. I probably should have caught that myself. They are still a 30-year old technology that are very damage-prone, expensive and time-consuming to repair and maintain, and are not nearly reliable enough for any industry other than space flight (for example, airlines). New materials are needed for sure, though I doubt you would disagree with that.
Well, that and one more factor: atmospheric density. Velocity and density pretty much determine your heating rate for any given shape.And yet out of all the factors you mentioned, the bottom line comes down to speed, temperature and the time spent at those conditions. Heating rate is determined by the velocity (effectively the convection coefficient) and the temperature of the boundary layer (itself a function of velocity and other smaller factors).
As for the rest of what you said, I absolutely agree. Fortunately, computerized methods are improving and computers are getting faster, but we're still a long way from a truly good understanding of what is happening and how to model it accurately.