One can also argue that other teams have adapted to us since then. Football and the world of football has been forced to evolve to solve our vaunted midfield and beat us.
Iniesta was a great loss. In some ways more than that of Xavi (whom I consider the heart and soul of Barcelona).
Zidane and Cristiano leaving Madrid (essentially disassembling Madrid) meant that we never got the chance to go up against the top Madrid team of recent times (some would say the very best Madrid team of all time in Europe) in an El Clasico Champions League Final.
Wonder who would win: 2015, 2011, 2009 Barcelona vs 2014 2016-2018 Real Madrid
2016 and 2018 Madrid aren't anything special. 2014 was very strong, 2017 their strongest ever side IMO.
In the forward line, you have BBC/Di Maria versus combinations of Messi, Henry, Eto'o, Suarez, Neymar, Villa, Pedro. Advantage Barca except for 2011 where I would say it's even.
Both teams play with a fairly high line with hyper attacking fullbacks. Xavi, Iniesta, Busquets, Alves, Abidal, Alba v Modric Kroos Isco Casemiro Marcelo Carvajal. Madrid's strength in CL has been a midfield/FB combination better than anyone else's in Europe. Unfortunately, we at one point had the best midfield of all time, indisputably. Clear advantage Barca
Defense/GKs: I think the combination of Varane, Ramos, Pepe has been better than Puyol, Pique, Mascherano. Better at scoring key headers too. TS is probably on par with Navas and Valdes probably on par with out of prime Casillas.
2009 Barca, 2011 Barca are favorites, 2015 Barca v 2017 Madrid is a toss-up.
What Madrid did better us (and every other club) at is consistency in CL. Their level in CL since over last 8 years (since 2011) is unmatched.
3 Semis, W, Semi, W, W, W