First, it makes turn-based games much more accessible and can greatly boost its number.
It doesn't necessarily, because the "Notes" system exists, and it is an arguably better system because you have to invest work in it, But this system just skips all that work and shows you everything immediately. So, it is strictly inferior to the Notes system.
Second, it makes the game accessible and enjoyable for a lot of players who do not like the memorization part of it. I assume this variant should be welcomed by the publisher.
Now here's the thing, you don't actually have to memorize "everything". There are few key hands which you have to keep track of, and even then, there are a few key cards that you should keep track of too (Notably, the 7th and 6th hand in a 4p game, and red/green cards).
It is also part of the skill, to determine which cards you should focus on.
This does require you to put a bit of work in, which may influence your other decisions. This tool, completely kills this skill aspect of the game
Now at first I didn't like the memorization aspect. But it gets easier as you get used to it, and it is rewarding. If you can just ignore the memorization aspect and have that all that information shown to you, focusing on the strategic aspect, you get a massive advantage compared to other players who aren't using this tool.
So, not only does this tool remove an important part of the game (the memorization aspect), it also forces everyone to use it to keep the playing field even. It also violates BGA's rules:
III-2 Be careful about player assistance
As a rule of thumb, in order to respect the original board games, you should not introduce any player assistance feature. An assistance must not be introduced if it directly helps the player to figure out if his move is good or bad. An assistance may be introduced if it can helps the payer to figure out what moves are available.
It would be fine if there was an option to disable it. And it shouldn't have been released if there wasn't an option to disable it in the first place.
But as it is now, it gives even less reason to play the arena mode.