Just because ships follow in the footsteps of others, it doesn’t mean that they have to look like them.
The subsystems that make up ships in New Eden are pretty versatile, and not custom designed for a single vessel chassis.
Often, parts are used across entire classes and ship lines.
So no, Jag shouldn’t look like the Breacher, the Hawk shouldn’t look like the Kestrel, and the Ishkur shouldn’t look like the Tristan 
Just because they have similar bonuses, doesn’t mean they need to look alike.