I think FP is simple, uniform and very powerful. Because of that it becomes easy to express very complicated things in it, and thus write complicated programs. Like Y-Combinator. FP is simple but FP programs (often) are not.
FP is a bit like Assembler. The building blocks are very simple. The resulting programs are not. In a more conventional language the building blocks are not so uniform there are many different things you build your program out of. Think COBOL. Not very abstract code at all. But easy to read.
Conventional languages are more like "Domain Specific Languages" where the domain is building business etc. software. FP gives you the full (?) power of mathematics, it is fully general, not domain specific. Yet DSLs are often a better fit for the task at hand.
FP is a bit like Assembler. The building blocks are very simple. The resulting programs are not. In a more conventional language the building blocks are not so uniform there are many different things you build your program out of. Think COBOL. Not very abstract code at all. But easy to read.
Conventional languages are more like "Domain Specific Languages" where the domain is building business etc. software. FP gives you the full (?) power of mathematics, it is fully general, not domain specific. Yet DSLs are often a better fit for the task at hand.