I think the only concern about the year is re: specs of the bike, just like a car. If someone tells you that they have a 2011 trek fx model over a 2014, you can then determine what the differences are. As the models progress, options from "higher end bikes" make it way down to lower end bikes so this is why the year is important to me.

In the end, at a very high level, it's a bike and it's all the same but the years matter if you are trying to buy a used bike. for example, is a 2011 trek fx 7.2 selling for $300 worth it? if it was a 2014 trek fx 7.2 selling for the same price, you know it would be "better optioned," just like a car.

an example in my case: a few years back when i got into the trek fx line, the 7.4's didnt have carbon forks.... i dont even remember what the old 7.4s were! lol... at the time, only the fx 7.7 had a carbon fork but that was a ~$1900 bike. but then when it came to buying an fx 7.4 this year, they are now including a carbon fork in the model and all the cables are routed through the frame like on madones and higher end bikes. these are cool features but i know if i bought an older 7.4, this would not be the case. i know if i bought an older 7.4, there's no way i would shell out $200 or $300 more to buy a carbon fork for it so it's nice that my new bike comes with one right out of the gate.

fwiw and ymmv.