Quick answer: Yes, there might be reasons, but they're usually not enough to prevent you from getting a great deal on an earlier model.
Compared to cars, when bikes change model years there may not be much, if any, material difference. The speed at which bike technology changes is slower and less abrupt.
As the general price of a bike gets lower, it's less likely a change in models / model years is going to mean a lot. Higher-end bikes are the ones where manufacturers usually introduce newer features and/or new technologies.
If you're considering something at the lower end of the pricing spectrum, I say go for the bargain unless you're sure the new model has what you really want/need.
If you're considering something at the higher end, you'll have to think harder. Consider what you might save now could cost you if you're getting old tech. For example, if you see a bargain on a 10spd road drivetrain, it's a trade-off because 11spd is the new standard and 10spd replacement parts are getting more expensive. A lot of times people get a bargain early but end up spending more in the long run on upgrades (see here: Save money by spending more - Buy the bike you want regardless of price).