Yeah but that injury came while riding in MotoGP, that lad went to MotoGP on the crest of a wave, 3 straight AMA championships and a WSBK championship as a rookie, brilliant first season at Tech3 then replaces Rossi, wins a race, gets a few podiums and very nearly won the Valencia race being pipped by Stoner then all of a sudden the bike's got issues, there's friction between him and team members(all while his teammate is battling for the championship), he starts crashing(something Ben was never known for), loses his ride to Rossi, moves to Pramac which I think is where the career ending injury happened and there was more friction between him and team.
I refuse to believe that he just wasn't that good, I think he was an exceptional talent, whatever ones opinions on WSBK what he did was unprecedented, he turned up with no experience of racing outside the USA other than a GP wildcard at Donington in 2008 and not only did he win the title he set records doing it and I'd agree that it was a tougher championship in 2009 than it is today.
But in my opinion it was the move to GP that did him in, same goes for James Toseland and while I don't rank him as high as Spies he was beating some bloody good riders like Bayliss, Biaggi, Haga and Corser, went to MotoGP and came back a shell of a man, again because he was treated like dirt, he got injured not long after and had to retire too but he did end up marrying Katie Melua so maybe he's the big winner after all.
I see the appeal of wanting to race in GP and Formula One because it is deemed the pinnacle of motorcycle and car racing but like I said it isn't the be all and end all, some racers never get to a certain level because of factors outside of their control, Matt Neal is a great touring car racer but at 6'6" tall he was never ever going to be a Formula One driver, just like Dunlop will never be a GP racer because he weighs 14 stone.
These series are deemed the pinnacle but that's just an opinion banded about, guys like Lewis Hamilton and Sebastien Vettel might struggle if they went to NASCAR or WRC just like Marquez or Lorenzo might struggle in BSB or Road Racing, different machines, different tracks, different competitors and different consequences.