Good question. Those H+Son rims use the plate over the valve hole as a counterweight to the rim weld which harkens back to the old days of the Ambrosio Nemesis, etc. A nice classic touch. Why would anyone want to use Schrader valves on bicycle tires?

With regard to the corsa controls, yes, very nice tires. You'll find that they stretch a bit over time, so they may have been a bear to initially mount, but once you get some miles on them, they'll come off and on easier.