I'm crying laughing right now. Businesses rarely see the advantages of upgrading something "Already Works". Now you could agree (and be right to a point) that it's the responsibility of developers/ops/etc to convince the business side but in my experiance the people writing the code are far enough detached from the people making decisions that they have next to no voice. My last job I saw an upgrade from Drupal 5 -> 7 and currently I work on framework that was last actively developed on 5 years ago (never versions have been released, they are now 2 major versions ahead of us which is a lifetime in PHP as of late with all it's changes). A lot of times you come into a place that is so far behind that to move up to the newest version would be equivalent to a full re-write (whereas moving up over time would have been possible had there been a bigger push for it).

I don't know if that contradicts what I said. If your upgrade strategy is "never," then no matter what the long-term support window is, you're going to go over it. If it's "only when I have to," making one obvious marker for when one might "have" to sooner rather than later keeps some people from falling so far behind that "to move up to the newest version would be equivalent to a full re-write."

Why would you care about end of life then, it works as is.

2 years is not a long time to migrate large system that works fine except for minor maintenance. It isn't just time, it is finding budget for churn work.