One simple reason: people don't value artists the same way they did back then, and artists need to eat.
Most of these sculptures (and the most impressive works of art in general) were commissioned by wealthy families, nobles, emperors, etc. Not to mention, many of these artists were born in favorable conditions. See, let's talk about these sculptures:
1: David of Michelangelo. Michelangelo's father was the town's judicial administrator. His family was bankers for generations (albeit smaller banks, still far above "peasants"). Later in life, he moved to Florence, which was basically the place to study arts. Art, in general, was really favored by the wealthy there: the council, merchants, and other rich people. Need I say more about his incredibly beneficial circumstances?
2: Abduction of Proserpina, by Gian Lorenzo Bernini. This was commissioned by the Cardinal Scipione Borghese. I could end the argument here, but his father always encouraged him in his pursuit for art, and he even got various patrons from an early age. Are you beginning to see the pattern here?
3: Corradini's Modesty. I don't know much about Corradini, but he also had various patrons. Curious, huh?
4: Ugolino and His Sons, by Jean-Baptiste Carpeaux. Jean had access to some of the best education he could get. His first studies were under François Rude, a famous sculptor at the time. I think it's enough, right?
The fact is that back then, the wealthy were more than willing to throw a fuck ton of money at artists, and they were willing to wait YEARS to get masterpieces. Compare this to now, where people barely want to pay you 10 USD/h and expect masterpieces in 2 weeks. Hell, even if your work is among the best in history, odds are, you're never gonna find a patron. Sure, PATREON is a thing, but even then, people are barely able to afford a 3$ monthly subscription for each artist they would like to support. When they are able to, they would also need to be willing to, and there aren't that many people who are both willing and with stable enough condition to support us.
Yeah, I would probably be capable of making a sculpture like this, and I definitely can make highly detailed oil paintings. The thing is: it's not worth it, because at the end of the day, I need to eat, and I can't eat if I am working on something that can take years without getting paid anything for it; or being paid as little that it might as well be for free.
You've just ordered Pizza Hut and a 2L Mountain Dew. You've loaded up RuneScape on your PC. No school tomorrow. Your parents don't care if you stay up all night long. A perfect Summer night. You are 39 years old. The year is 2022.
@stoneshoretrpg Wandering Swords boasts a unique combat system which really encourages players to learn each foes moveset and react to monster tells. This among many other design choices, make this the perfect game for a short souls-like campaign.