Too much average coffee
Once upon a time, most caffs served instant, usually fairly cheap stuff.
Now they've mostly put in an espresso machine, but the coffee is still pretty poor, though not as bad as the instant. It gets tarted up as cappuccino, latte, and so on for a dozen options, but the beans are anonymous and undistinguished
The pretentious big chains are the worst - Starbucks are pretty awful, Cafe Nero better. Coffee One is the best, with real bean choices, but only in the West of England and south west Wales.
What has almost entirely disappeared is the coffee shop offering an interesting range of beans and roasts, with a simple sandwich, cake or biscuit to accompany it. Regional Beans, single estate, custom blends etc. etc.
The best I know is in Saffron Walden (east England near Cambridge, and I live in west Wales), who are the only place I know to offer the Civet coffee. I don't know the name of it, but if you are around there it is near Waitrose, and really worth a visit.
And now I've got to go and put a brew on.