The only real problem is that manufacturers lag behind on updates so much that the 2 years is actually only a 1 year equivalent to nexus/ pixel supportIt was flagship device in 2015 and part of the 2016
Now it's not priority one device as new flagships are here.
But IMHO 2 years of support is joke, it shold be 3 at least or they should release crucial parts of source code for open-source community to give them chance build good ROM with all the "qualities" of the stock rom (I mean camera quality as example)
2 years is plenty if the manufacturer provides mayor updates all the way untill the end and doesn't just essentially wait out the 2 years. For example if we get nougat in q3 that shouldn't be considered long term support from LG, when nougat was actually released when this device was just over a year old. So the 2 year support should count up to when the os was released rather than when the manufacturer decides to release the update.