In a spreadsheet, I need the dot separated date in YYYY.MM.DD format, e.g. 2015.01.012015.12.11
In the Format Cells dialogue, you can create your own "User-defined" formats. Just enter your "YYYY.MM.DD" in the "Format code" box there. Some formats get complicated by locale-specific properties, but I doubt there is any problem with this one.
Alternatively, you could always create a formula to develop from a genuine date value a text string (in a separate cell) representing any format you wanted.
Should I file a bug report to add this feature?
Probably not.
Is it currently not available?
It is - as above.
I trust this helps.
Brian Barker