Tuples require object deconstruction syntax. KatLang does not have object deconstruction feature. KatLang has simply deconstructed the function into input and output. In KatLang you define algorithms by specifying inputs and outputs. If You use implicit parameter, then the algorithm has an input. If You do not use implicit parameters, then the algorithm has only output and it is more like a data structure rather than a function.
I agree, that parameter ignorance operator # is ugly. I do not like it. The plan is to remove it in the future versions, but it requires some research.
About expression reading and parsing... Your argument is correct, but KatLang expressions are relatively short. I do not expect that KatLang will replace general purpose programming languages. KatLang is just a simple language for calculations. Main goal was to redesign the calculator and KatLang is good for that.