Every waking day of every waking use of the devices I have, I find myself constantly fighting a lot with the shitty input and recognition of said input. Things I swore I clicked once but having to click twice or sometimes three times. Such lag input between the last time I clicked and to the time the function of whatever I had to click fucking functioned.
With phones it is obviously worse, with finger input being either too sensitive or too dulled to register, inquiring more touches just to get somewhere or to type something, along with the separated frustrations aside trying to type on awful keyboard interfaces.
I started with 2.3, it was a bit daunting. 4.4 though was so fun. Even up until like 7 or 8 I remember rooting via a simple app and then the world was your oyster.
On the topic of practical changes, it took them until 11 to add an audio output switcher to currently playing media notifs and even then they made them far uglier and less functional.