RETIRED Pornstar, Service Plumber
Depends on what you consider as the "valve". For a two handle ceramic, yeah, you're just going to replace the cartridge/ceramic stem. I've seen replacement ceramic disks with bottom washer and I think that's ridiculous because the ultra low lead brass they use nowadays corrodes so easily they aren't worth rebuilding................there seems to be less repair and more of replacing the valve. What tools would help the repair plumber? ............
There are plenty of specialty tools made for specific circumstances. The only tool I would currently like to see made is one that used to be made, the sexauer slide hammer handle removal tool. I added an 1/8" drill rod to the tip of one to aid in pulling handles off by simply screwing the center in.
As for how you could really help us service plumbers, get involved with "Tapmedic". Help make their stuff more available here in the states. All modern two handle ceramic faucets and many ceramic diverters use pretty much the same cartridges just with different spline counts and bonnet threads.