Perculiar Named Calculations

In regards to this article about named calculations in SSAS, I had the perculiar finding today, that NULLs are handled somewhat differently than I would have expected.
In my case I had constructed a named calculation, just as in the article, by concatenating two columns, both of type string and allowing NULLs.
The perculiar part was, that when the second value was NULL, the whole expression would result in a NULL.
So, in order for the concatenation to succeed, the expression should be as follows:

[Marital Status] + CASE WHEN LEN([Has Children]) > 0 THEN  ‘ ‘ + [Has Children] ELSE ” END