Depending how you define sounding rocket the title of heaviest/largest probably belongs to a V2 derivative such as those flown during the Bumper program with masses around the 12-13 tonnes though finding actual launch mass of the various combinations is challenging.
After that you get into various ICBM and launch vehicle tests in the 15-30 tonne range that flew sounding rocket profiles and in many cases carried science payloads but were flown more for testing the vehicle rather than the payload. These include Mercury Redstone and the British Black Arrow/Black Knight programs.
Finally there are things like Ares I and Project High water in the 100s of tonnes class but generally flying somewhat normal launch trajectories that just happen to be sub orbital because there is no second stage and only flown once.
The main reason for this somewhat odd '1940s being the biggest' is cost. It does not actually take that much of a rocket to fly a single 10-20kg instrument above the Karman line (even in 1960), per the table in the question. If you do actually want to fly a 100-1000kg payload the cost of building it probably means you want more than a couple of minutes in space, and building one and flying it as a satellite makes more sense than building a dozen for short one way flights.
Larger rockets also become entangled in ITAR where unguided & lower payload models can be more widely sold.
So there is little commercial incentive to design, build and sell a 10-20 tonne rocket to fly sounding profiles with 1-2 tonne payloads so none have made it to market in volume to be used for sounding rocket programs.
The answer to this question may change if the 20 tonne New Shepard starts flying science payloads on a commercial basis.