Kobe taking a ridiculously huge contract does hamstring the Lakers, but I'm not sure he can really be "blamed" for that. I guess you can argue he should have opted to take less money for the good of the team, but I honestly don't think he owed them that. He did what the overwhelming majority of players would do, and took the best deal he could get. If someone is to blame there, it is the Buss/Kupchak brain trust for offering him a deal everyone knew made no sense at the time.
Kobe being a gigantic asshole, on the other hand, probably has hurt them...on the other hand, its not like Shaq was on great terms with most of his former teammates, and Dwight isn't really known for great team chemistry either. I think both of them share some of the responsibility for those teams falling apart as well. Shaq in particular was massive (in more ways than one) diva with probably the worst work ethic of any NBA superstar ever--during those Lakers years he'd regularly show up to camp 30+ lbs overweight, having spent the offseason eating, running his mouth, and doing stupid media stuff, then he'd play himself into shape over the course of the season so he could steamroll a weak crop of centers over the playoffs, all while talking himself up and taking as much credit as possible for the team's success. Kobe, being a workaholic Jordan wannabe, may have dealt with this especially badly, but I honestly think Shaq would get on most NBA superstar's nerves if they had to share the spotlight with him. As for Andrew Bynum, his bad attitude was proved beyond a shadow of a doubt to have everything to do with Bynum, and nothing to do with whatever poor team happened to sign him.