Honestly don't think that's entirely fair though. I do think outside distractions play a role for some players to their detriment like Ivanovic or possibly Bouchard (though it's hard to tell what the hell happened with her, probably just wasn't good enough in the first place), but others like Azarenka and Kvitova had other issues. Azarenka really suffered from injuries which is why she declined for a while, but I think she is probably the number 2 player on tour when healthy. Kvitova is purely a grass player which is actually a big problem in the WTA. There are way too many players which can only play on one surface, like Errani on clay for example and they literally lose in the first round on any other. This kind of extreme is not as common on the men's tour.
At any rate, I do believe that modeling/acting/etc. are distractions for some players but definitely not for all of them, and there are other reasons why there have been some slam winners who have not truly broken through or have disappeared a bit. In the end though, regardless of anything else, they still would have been dominated by Serena in the end.
As a Federer fan, I'm loathe to hold the weakness of the field against Serena, as this is a flawed argument that has been used to diminish Federer's dominance in his prime. However, one thing that is disconcerting about this generation of women's players is not that they can't beat Serena, but that many of them don't even show up at the end to give her a go. Kvitova (the one player you could see beating Serena) was ousted in the 3rd round of this Wimbledon, while the likes of Wozniaki and Ivanovic often fall early. This has left Williams facing the likes of Muguruza (who does look to have great potential, but is still very raw,) Safarova, Wozniaki and Radwanska in finals in recent years (all of whom you knew had no chance.) Compare this to the preceding generation, of which Serena was still the leading player, which boasted the likes of Henin, Clijsters, Davenport and Capriati.
Federer in his prime was dismantling the likes of Agassi, Roddick, Hewitt and Safin (who collectively won 12 Grand Slams,) while holding up his end against Nadal and Djokovic (admittedly yet to reach their primes.) Safin was a bit of a head-case, but had the talent to beat anybody (perhaps Kvitova is his equivalent,) and Hewitt, in my opinion, was an earlier version of Murray (ie. he had the talent to be a top-four player, but had the misfortune to enter his prime at the same time as Federer, much like Murray with Djokovic and Nadal.) So I think that the men's era from 2003-7 was not as weak as it looked; rather they just had the misfortune to be playing during a period of unparalleled dominance by one player (in the men's game, that is.)
Anyway, this is all a bit rambling. I guess the question is: is Serena the greatest player of all time? Would she match up against the likes of Navritalova, Graf, Evert and Seles?
