As the icons progress to the left, identification increasingly depends on colour and shape. Since there are a limited number of colours and shapes, they tend to get reused. This increasingly leads to mis-identification of icons.
This is particularly true for the visually impaired and some elderly and neuro-atypical people.
What matters in an icon is uniqueness. Only the skeuomorphic icons to the right can be unique enough for proper identification.
Trendiness of visual appearance has no place in the functionality of a complex machine. If you think it does, I submit the following for your consideration: you. are. a. monster.
Yes, I said that and I mean it. You followers of Jony Ive and his ilk are assholes. The rest of us don't give a shit about your design schools. We just want to be able to click on the right thing.
Hate me, but it's true.