I don't understand thrust stun. I can rarely punish anyone for it. I block, do an attack as quick as I can and they just block my swing. Same when I chamber the stab. Besides, you gotta take this out of classic duel situations. In battle the 2h stab is an amazing attack which allows you to double as a sort of support polearmer and allows you to deal damage in big group versus group situations, while a 2h is one of the best 1 vs 1 classes. In murica you all seem to get by with bec de corbins and longswords so I am not sure if you have as much group versus group situations where everybody is covering everyone, but in EU having an attack that is 1.5x your usual reach is incredibly valuable.
Also, go on duel, pick a cookie cutter longsword build and only use the stab and risk spamming it, see if you can beat anyone with just stabs.