TMA already has themes - kata. In sanchin, it's rooting and breathing. In seiunchin, it's grappling. In Kusanku, it's double striking and evasion. Joint locks or strong blocking and striking may be the theme in others. Often, a kata will incorporate several of these.
In practicing, one can concentrate on power, speed, flow, simultaneous blocking and punching, side stepping and other footwork, close-in or long-range fighting technique (or transitioning from one to the other) etc.
But I really don't see any of these things as a "theme." It's just developing various skills that can be combined to use in a fight. I think it's very difficult to hold on to a theme in an actual fight as the dynamics and conditions change. You use whatever you can in that specific moment. The closest one can get to a theme in combat is a general strategy based on the battleground and opponent's abilities/tendencies.
If you want to call practicing a particular skill set or a particular way of executing a technique a "theme," I guess semantically it's not wrong. I just call it training.