ISO 9075 is the official SQL language standard (synonymous with ANSI SQL). It has supported the double pipe for string concatenation since 1999. Almost every other database supports this operator (the tragically broken MySql reinterpretation being the prominent exception - but who cares?), and thus makes generating more universal SQL cleaner and easier... except that SQL Server doesn't support it.

You can change that. Vote on Connect: https://connect.microsoft.com/SQLServer/feedback/ViewFeedback.aspx?FeedbackID=259291