Surely the fact that the temps are 2c colder shows that the heatsink is disipating the heat even before reaching ambient air ?

I wouldnt call that inaccurate. In much the same way, if you wave a IR reader over a CPU heatsink, it'll be colder than what the CPU tells you.

the modules simply don't get hot enough to warrant a super-close eye on temps

Crucial obviously had some time to spare. At least this feature is at no extra cost and no other manufacturer needs to bother with R&D on this gimmick.

data-obsessed enthusiast

Surely the obsessed will be going for lower CAS ratings as this model seems fairly typical of other brands' value/midrange models, nothing interesting at all going on with this release in my eyes.

Perhaps some benchies… if no other hardware gets released anytime soon. :p