Any use for coins/tokens of defunct projects like Synereo/Hyperspace (AMP) and others?
Yes, they can be included in this list,
https://deadcoins.com.
Seriously, common sense dictates that can there are no used for them anymore. Perhaps we can learn from their mistakes or developers look at what they failed and not create similar projects with no use case at all.
And I would say that majority of coins/tokens that has been hype around 2017 could be dead by now or in the process of dying.
It is just common sense as you say but the majority of people simply cannot accept that they made a mistake when they pick a coin and they fail, it is in fact a very natural reaction but one that is not very constructive if your aim is to become a successful trader in the future, at some point people that invested in those coins need to accept they made a mistake and that they should begin to to try to understand why this happened to them so they can avoid this to happen again, but very few have the introspection necessary to do something like this.