Turing completeness is a bug, not a feature. After writing code in Agda for some years I was convinced that Turing completeness does more harm than good. Non-TC languages have a killer feature: their halting problem is solvable which means you can get arbitrarily strong guarantees from the compiler. The fact that you can't encode "while(true) { }" without putting "unsafe" doesn't make the language impractical, you can still implement algorithms without Turing completeness.

Moreover, using various forms of coinduction you can encode infinite computation even in non-TC languages.