No you shouldn't feel that way. The engine manufacturers tend to do things like increase the engine displacement a little as a marketing ploy to get you to buy newer, the latest and greatest and so on. Now if your plane is flying great with your current engine, you do not need to "upgrade" just because they came out with a newer, bigger engine. Now if you were in the market for a new engine for a plane, then yes the latest and greatest may be the way to go. Unless they have a good sale on the older model going on though.

I am still using and flying a engine on a plane made back in the late 1960's. It still runs good and pulls the plane around just fine. So since it hasn't worn out why replace it, if I don't need to. Yeah I could have put in a new fancy modern Schnuerle ported wonder engine, but it wouldn't gain me anything except making my billfold more light.