Why run or have track and field in the olympics? Certainly cars or even basic scooters can outpace the fastest human. So what? It is interesting in its own right what humans can achieve performance wise, with their flesh and blood constraints.
Chess is solved by quantum computers, so WHY PLAY???

they can, actually
chiaroscuro62 wrote:
Except currently quantum computers are completely feeble. My cell phone is a GM but quantum computers can't do elementary arithmetic.

Chess is solved by quantum computers, so WHY PLAY?
An excavator is stronger than a man, so why powerlifting?

Because its a game and its fun? If it bothers you so much that the game is solved by computers, why don't you just stop playing and stop bumming out people who actually enjoy the game?
Let's say one day the calculation from the opening and the endgame calculation (tablebases) meet and chess is "solved" - be it a draw or win for white. Then you have a kind of "perfect" line for white and black. You can memorize it, no problem. But what if someone deviates from it on move 7 and plays the 2nd best move ? The whole line becomes rubbish and you need to find the way to win/draw all by yourself from this point. What if they deviate on move 3 and on move 37 ? Or deviate a on every 5th move ? If you want to memorize every line and every perfect response after every deviation, a lifetime span will be too short to do that. So chess is not in danger by that. The danger for chess might come from cheating, when technology becomes smaller so that one can hide it in a contact lense for example.
If I have a mate in one threat and there is one way to block it I will find lines after the block only and won't consider lines where my opponent doesn't.
As for the question...
Mate in ones are already solved - and you don't need a computer for that. The "solutions" for 6 or 7 piece endings on the board need a stogare of 140 000 gigabytes. And when people say "chess is solved", that means with 32 pieces, a secure way to draw or win from move 1. And this will require to memorize a number of lines that takes more than one lifespan to even read them, let alone memorize them.