Fluent is attacking multiple problems.
On the surface, it blends APL and LISP. Making S/M-exprs terse and building “diamond-less” left-to-right APL on top. This part is pretty okay.
In core, unification of FRP and AD as already mentioned. This is mainly to do efficient online/incremental learning. Currently this is a disaster and main source of tech debt. I got some attacks.
Fun and curiosity is the main motivator. Having single system that can do user-editable explorable ML explanations is just cherry on top.