I'm in the UK. I go to many high-end restaurants, cocktail bars, etc. Portable card terminals are essentially universal in these places. The fact it's the same everywhere is a feature, not a bug.
It's quick. Your card never leaves your sight. No pen is required. Payments up to £100 can be done using contactless on a physical card. Even higher amounts with smartphones/smart watches. Tipping is often integrated into the terminal where tipping is common. It's rare to have to put the card into the terminal.
I don't think it detracts from the experience. On the contrary, I think it streamlines the bit between being finished and wanting to leave:
"Please can I have the bill and a card machine, please".
They’re almost universal at this point to the extent that not to have one would be unusual.
Where you live maybe.
In Japan, you don't pay at the table, you get up when leaving and pay at the exit. If you're at a high-end establishment entertaining guests, this also leaves you the opportunity to "go to the restroom" late in the dinner and pay ahead of time so that the "mess" of payments is completely forgotten.
It also means waiters don't need to run around the place with cards/readers/cash, you don't need to fumble when you left your wallet in your coat that's been hung up, don't need to squint to read receipts in the dim mood lighting in the eating area, etc etc.
Some (well, one maybe) restaurants near me are like this but it is uncommon. Ram's Horn comes to mind.
I do know that some restaurant owners are removing these things. They do not want to look like Olive Garden :)
But it really depends on a restaurant: is it high end, type of food / drinks, it is a date place, etc.
Majority of restaurant is all about experience and event payment system should match that experience.