If it does what the user needs it to do reliably and on acceptable terms to the user in question, how is it not in good working order? What percentage of XP users do you suppose would disagree with you about whether their systems are working acceptably?
If I saw something in real world terms (e.g. Windows 7 typically has 12 critical security vulnerabilities patched by month whereas Windows 8x typically only has 6) that clearly demonstrates Win8x's superiority in this regard, I might be inclined to agree. However, AFAIK, pretty much every vulnerability that affects Win7 also affects Win8x to the same degree. I just took a look at MS's vuln list published in January 2015 and what I said agrees with that, with one further point that there was one Win8x specific vulnerability that Win7 wasn't affected by.
Otherwise "out of date" is as pointless a term as "obsolete", you may as well say "it's not the latest version", which carries as much implication as "black is not white". If we're going to use specific terms, they've got to mean something useful.
For desktop computer builds, I give my customers the choice between Windows 7 and 8.1. The cost is just the same, and even though I prefer Win7, I recommend Win81 because its expiry date is 2023 as opposed to 2020. I then reassure any potentially jittery customers on the topic of whether they'll go on with Win8x that I can make it look and work very much like it does on older versions of Windows.
They are not working acceptably. It may be fine to you but XP is a security black hole to everyone else. Junk been holding everything back too. MS should have executed it back in 2007.