Let me just start this by saying I have no problem with Rosberg on a personal level, and I don't enjoy moaning. This is just what's topical at the moment.
Unlike most, I think Nico's decision to retire is actually cowardly and disrespectful. I criticised Rosberg before for taking the easy way out of the championship, not proving he deserved it or giving us the excitement we were desperately expecting. To now retire having just won his first, and now only world title, implies he doesn't believe in himself enough to beat Lewis, or any other team or driver he is wary of for next year. I can imagine his fans must be devastated, having finally been given rightful confidence in their driver, as he should surely have in himself, only to see him take the easy route out again. Nobody can now prove they are better than him, nor can he finally prove his skill by trying to defend his title, or at least win a second one, or one with another team.
I also find his career motive questionable. I have never before heard of a driver not trying to earn themselves a second championship. Even I know from my karting days how addictive winning as, as was immortalised by Senna's words to Mansell following Nigel's 1992 glory. Again, I can only assume Rosberg is scared of not being able to emulate this success, maybe he does feel he was gifted the title through the luck of the racing Gods. If so, I don't believe that's the right reason to be in the sport. Perhaps he was just in it for the money, but I can't bring myself to believe that either.
Nico claims he wants to spend more time with his family, a worthy cause of course. Everyone knows that racing in Formula 1 and raising families don't really mix, both require far too much commitment. Some manage it, take Felipe and Romain for example, but most don't. Most wait. As Jenson said, "you have to be selfish in this sport". It is very rare to be both a dad and an F1 driver successfully, so if Nico really wanted to spend more time with his wife and daughter, why did he not retire or take a sabbatical when he first got married, or when his daughter was born? Or, like most, why did he not wait until the end of his career to raise a family, in order to actually relax and enjoy the his first few years of being married and a father, raising his child rather than travelling the world. It's a sacrifice that usually has to be made, I think Rosberg's planned it very badly. He must think so to some extent, or surely he wouldn't feel the urgent need to retire at the peak of his career to rush back to his family.
Toto Wolff and Niki Lauda must be absolutely appalled. Toto claimed to know nothing about this decision, saying it caught him "completely by surprise". To sign a multi year contract to the team he's been racing for for the last 6 years, who are currently the number one team on the grid, the ultimate engine supplier and the team who have given him his only real opportunity to win races and a championship (which some of my friends still believe is a conspiracy against Lewis) in the past and future, to go and rip up the contract in between seasons, leaving Mercedes with a huge great gaping driver-shaped hole in one half of the team, I think, is utterly disrespectful. That's no way to repay them. To have not even discussed it or mentioned it to his superiors is shocking. It leaves them in an undeserved, unexpected, awkward situation.
Jenson, Felipe and many other drivers like Romain, Hulkenberg, Magnussen, Vettel, Alonso or even Ocon must also be furious. Jenson and Felipe both seemed happy with their decisions to retire, but if they'd known a potential Mercedes drive had been on the table, I'm sure they would've thought twice about their options. Likewise the staple midfield talents, Grosjean, Magnussen, Hulkenberg, Perez even Ocon looking for a big scalp to rocket their careers forward, no doubt would have pushed Toto and Niki for a chance to prove themselves. Nico has denied them this opportunity to advance their careers by making this late, unannounced desicion. I;m also certain that Vettel and Fernando would've both also been very interested in a Mercedes seat... We wait to see who will replace Nico.
I don't mean to pick on Nico, and as everyone does I wish him and his family all the best in this new path of their life. I do think Nico has gone the complete wrong way about doing this though.