WEST SIDE STORY --> Tony in the Movie Version
The only way he could really have been worse is if he didn't know the lines. You
may have liked Richard Beymer more, but that doesn't mean he was better than Matt Cavenaugh. Cavenaugh may have lacked the charisma to inhabit the role fully and make Tony as dynamic as he could be, but that has as much to do with Arthur Laurents's conception of the character in the way he wrote the role and in the way he directed the revival and the casting itself. In that regard, Cavenaugh may haven been as miscast as Beymer was, but at least Cavenaugh did his own singing thereby actually playing the role in its entirety, something that Beymer can never claim to have done.
Street gangs of the 1950s weren't quite what street gangs were to become as the 20th century continued and West Side Story
is a poetic interpretation of what street gangs of the 1950s were like. Add to that what we actually learn about the Jets in the show: that they talk bigger than they act and that they appear to be relatively inexperienced beyond playground fisticuffs. Tony may have been a Jet, but perhaps expectations of what the Jets are is a bit overblown: they're not a slick, hardcore operation, but a ragtag bunch of restless teenagers that are find themselves in a situation that spins violently out of control. I'm not saying your point is invalid, but I am saying that there is a delicate balance at play here: it's a bit more complicated than simply playing it one way or another. Pushing the character too far in the opposite direction could be as destructive to the show and actually even more so: one risks losing the contrast between the Riff, the other Jets and Tony; the motivation for the conflict within their own group regarding why they should involve Tony in their affairs at all given the change in behaviour and his abandonment of the gang; and the very thing that makes Tony attractive to Maria, that he there is something obviously different between him and all of the men that she knows and sees and not in a way that echoes the relationship between Stella and Stanley Kowalski in A Streetcar Named Desire