Shimano is typically on a four year cycle regarding group upgrades. Dura Ace being first, then Ultegra, then 105, then whatever is below that, etc.
The updates are usually small but well thought-out so if you have the previous version you aren't really that far behind.
I wouldn't worry about it and if you like the bike, buy it.
The Classic and Vintage folks are riding stuff older than your parents and having a blast.
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