It's true that many of us are tennis tragics, but some of the criticism in this thread is not a value judgment about modernising tennis from that perspective. Some folks are strictly focusing on the failure in execution of the new UTS concept.
And I'm inclined to agree with them. Putting aside the issue of whether it's good or bad to be retooling tennis so radically, there are just basic errors in the way they have done UTS so far that limit it's appeal to younger audiences.
@Bobby Jr mentioned one of the biggest mistakes they have made so far - If they want to visually engage younger audiences a good place to start is high-quality match camera coverage. In the initial UTS coverage they have used a very fatiguing, boring long camera angle for the play-by-play footage which is less visually engaging than what already exists. USTA has been broadcasting hours upon hours of this type of "fence-mounted" footage for years and it is not a good way to showcase the new format.
Another concern is that they are entering a global market without the best global talent. Casual fans will only tune in if they are assured they are watching the best of the best. WE know guys like Gasquet, Goffin, Pouille, Tsitsipas, Thiem are great players, but only because we are tennis nuts. There are no men's singles major winners in the men's playing lineup, and casual fans won't tune in for that.
The other problem is the marketing concepts.......Framing the players as generically as "The Greek God"...... "The Rebel" - you must be joking. Young people have never had more access to sophisticated screen-based narrative content and quality screenwriting / character development / performance etc etc. And if they want silly/boilerplate stuff they have fonts of reality TV to enjoy. Mouratoglou harped on about UTS being a way to magnify personalities and bring new people into tennis, and then presents them like this? It just won't cut it.
Sorry for the rant, but all of the non-sanctioned tennis events that have popped up during the Co-ViD crisis (UTRP / UTS / Djokovic's thing) have all had a bit of a "yucky" quality to them in my opinion. Most of them just seem like land grabs - startups trying to capitalise on the vacuum in tennis and snatch an existing/emerging audience for their content platforms while the real tournaments, and most of the sport, is justifiably still in lockdown mode.