The reason is that the tokens do not have any real utility and people would sell them massively on any sign of something bad, like a very negative media article. If they were so good, they would not need to be staked to prevent users from panic selling. 
I may not totally agree with you on where you said that the reason why most utilities tokens are staked is because their lack real world utilities feature, that is a false assumption to me because if you check you will see that most cryptocurrency lack the real life utilities Aside from being treated as an assets, even Bitcoin falls to that category. If you said lack of liqudities on exchange to keep them tradebel or low price that kills traders and investors motivation to use them on exchange.