How far does "non turing completeness" really get you in this context? It looks easy to write a program in this language that will take longer than the age of

How far does "non turing completeness" really get you in this context? It looks easy to write a program in this language that will take longer than the age of the universe to evaluate and whose result can't be represented explicitly without collapsing the galaxy into a black hole. How much comfort can you take in the fact that you know it doesn't diverge?