Heh... bear in mind that I'll be 65 this coming October, started programming about the same year you were born, and was also a DoD employee for about 15 years (Raytheon, Submarine Signal Division, Portsmouth, RI) after a 9 year stint in the U.S. Submarine Service. I wrote my first program in high school back in 1967 but I'm certainly not the oldest one out there.
I'm with you on the implied subject that new isn't always better. In fact, I strongly embrace the mantra of "Change is inevitable... change for the better is not". On the subject of the IIF function, apparently MS agrees because, in execution plans, it renders out as a CASE statement. Although I love the CASE statement, IIF is kind of cool because it reminds me of much older programmability in the form of "If, Then, Else" in one tight little statement. To be sure, though, I am loath to nest IIF functions before my 3rd cup o' joe and normally revert back to CASE statements for such things because they are, indeed, easy to read and understand especially when thoughtfully indented..
I'm also loath to do things outside of SQL Server even though a lot of people preach "Just because it can be done in SQL, doesn't mean it should". My typical reply is "Just because it can be done in PowerShell, C#, PERL, PYTHON, or a thousand other languages, doesn't mean it should". When they come back with "Well, SQL Server isn't the center of the universe", my reply is, "True... but let's turn yours off and see if it's the center of your universe".
Don't get me wrong. I'm not opposed to using the right tool (ex. I've used PowerShell to greatly simplify an enterprise-wide disk-health morning report) to simplify things but I'm not prone to using something new just because it's new. A really good example of that is the relatively new FORMAT function (44 times slower than CONVERT) and that god-forsaken PIVOT statement (twice as slow as a pre-aggregated CROSS TAB).