I feel that the OP misunderstands TeX's virtues: it is a very powerful typesetting system whose macro system happens to be Turing complete. Typesetting is the hard problem and TeX has solved it so well that most people wanting to build a text-driven typesetting system has built on top of TeX rather than trying to replicate it. This is especially true for typesetting equations.
If you try to use TeX as a programming language, you're going to be disappointed, as the OP seems to have been. The macros work well enough for saving typing by making simple substitutions, which is what most people use them for. But using them for anything more complicated is a bit of a black art. Somewhere I read that Leslie Lamport wrote out LaTeX in pseudo-code first and then translated it into macros. Knuth was impressed by what Lamport was able to do with a system which was not meant to be a general-purpose programming language.
In the end, I think Knuth was correct to make TeX's input focused on document entry and not on programming. I've never used it, but LuaTeX seems interesting because I think it's better to use an external language for programming rather than one embedded in a document layout format.
If you try to use TeX as a programming language, you're going to be disappointed, as the OP seems to have been. The macros work well enough for saving typing by making simple substitutions, which is what most people use them for. But using them for anything more complicated is a bit of a black art. Somewhere I read that Leslie Lamport wrote out LaTeX in pseudo-code first and then translated it into macros. Knuth was impressed by what Lamport was able to do with a system which was not meant to be a general-purpose programming language.
In the end, I think Knuth was correct to make TeX's input focused on document entry and not on programming. I've never used it, but LuaTeX seems interesting because I think it's better to use an external language for programming rather than one embedded in a document layout format.