I don't see it. For me Mathieu, Hummels, Silva and Ramos are not on par with Maldini, Hierro, Nesta, Blanc, Montero and Ayala. Nowadays is very hard to find a defender that is excellent in both defending and ball playing skills. Ramos has been a large question mark in his defensive duties and it is since couple of season a center back, most of his career he has been a right back. Hummels is not very consistent and his lack of pace is exposed nowadays on more than one occasion. Mathieu I wouldn't rank as one of the best defenders and Silva is probably the closest you get to those mentioned above. Rio was a freak of nature, no one comes close to the all round package he had in his locker. Let's not forget that 2-3 months ago when LvG said that he wanted a ball playing defender how everybody struggled to name one who was also good at defending.
Here as well is worth mentioning that quality full backs are also a scare commodity. In the past we had Lizarazu, Carlos, Cafu, Maldini, Panucci, Zanetti, Thuram... Now Luke Shaw who was pretty inexperienced is worth 30m pounds and as we needed a quality RB this summer out of the most of the established names that came up was Dani Alves who is nearly retired.
Atletico's success is generally due to Simeone. Having a great manager is the #1 priority when you are trying to build good and successful team(something we're learning the hard way after Fergie). Luis failed at Chelsea, Godin and Miranda were already there until Simeone took over. Before he did, they conceded 26 in 16 games and 53 goals the season before. Only afterwards they began to tighten the defence, and besides if you see Atletico regularly they defend all over the pitch which helps a lot.
The quality of attackers nowadays is a bit questionable as well in terms of individual. From the top of my head I can think of Lewa, Benzema, Ronaldo, Diego Costa as world class strikers this year. Feel free to add if you think of more.
Costacurta in the 90's was pretty consistent and free of injuries. Let's not forget that the calccio was 18 teams and they had to play 4 games less every season. He rarely missed more than 3-4 games per season in Seria A. Also in England there are more fixtures due to the league cup etc..
Well there are other names that I haven't mentioned, those were just cream of the crop, but there were also Tasotti, Ferrara, Iuliano, Torricelli, Couto, Sensini, Benarrivo, Reuter, Irwin, Popescu, etc.... I'd say if you look at the defenders individually, the quality in both defensive and ball playing skills was better, of course the tactics have changed and overall football has moved on in some directions so possibly this takes part as well.