I don't mean to be a ****, but if I hear 'it messes with established cannon' one more time, I am gonna throw poo.
hell, lucas himself couldn't even keep track of what R2 units were compared to R4 units in the prequels.
Update: well, I woke up on the wrong side of bed this morning! Sorry all......
I guess for myself, I do not mind new designs cause I look at it like this: we never saw Biker Scouts until the 3rd movie. Now, we can assume it was a new design as of that movie, or it was just something we had never seen up until then! Same thing with Rogue One.
Personally, love the idea of new designs, like the Deathtrooper and Shore trooper. Can't help folks if they hate the redesigned Stormtrooper, but from a practical standpoint, I 'get it' stunt people need to move better.....