The same "edged weapon vs. heavy armor" issue existed in Europe. Striking plate armor with a longsword might not cause it to break, but it'll ruin the edge. You just rarely ever see this issue expressed in the rules. 
Just my personal opinion, I like this particular rule. IRL, any samurai or knight would think seriously about what weapon to use against a heavily armored foe. The crab are big fans of the tetsubo for exactly this reason. Samurai from other clans are much less likely to encounter heavily armored opponents, but still often carry yari if for no other reason than that it's just poor planning to only have one tool in your toolbox. 
 
 

FWIW, my group and I are really liking the beta so far. Our ages range fro 41 to 52. Not exactly a table full of millennials. 
 
 
Es un cambio mas grande de lo que esperaba. Pero sobre la misma cantidad de cambio que EotE fue de anteriores juegos de Star Wars.

FWIW, my group and I are really liking the beta so far. Our ages range fro 41 to 52. Not exactly a table full of millennials. 
 
 
Es un cambio mas grande de lo que esperaba. Pero sobre la misma cantidad de cambio que EotE fue de anteriores juegos de Star Wars.

FWIW, my group and I are really liking the beta so far. Our ages range fro 41 to 52. Not exactly a table full of millennials. 
 
 
Es un cambio mas grande de lo que esperaba. Pero sobre la misma cantidad de cambio que EotE fue de anteriores juegos de Star Wars.

I'm going to go out on limb here and guess you didn't like it?