So we've sort of decided to apply 'twinking' as the ability to stat your character to maximize their potential in a certain direction, usually pretty focused. What is wrong with that? To be honest, I would rather have that than everyone be a jack of all trades. I like the new GMC XP syste (similar to oWoD) in that the difference between 3 dots in a skill and 4, is not a hell of a lot, but now, 3 and 6? Now we're getting somewhere. With the current system, everyone can have 3 dots in everything, specialize for 4 dice base skill and still have tons of XP left over. Specializing actually costs you a boat load of XP.
But think of all the games you've played, old D&D etc, there were classes, each class did something well. Other classes could find ways to do what another class did, but it was usually a challenge. It is one of the reasons I love Werewolf. You have a pack of wolves (a team) and why would you not want to have every member specialized in a various area so that as a whole you were much stronger than the sum of your parts? This is where I think what you've defined as 'twinking' should absolutely come into play. You find a problem, AKA you need to sneak in a steal a painting, you send in your thief. Got issues with spirits, you send in your Spiritmaster, rituals? Ritemaster, etc etc etc.
So to me, I'd rather see people good in one area and meh in others, so that it facilitates everyone getting a moment to shine.
That ties me into that comment that Somasatori posted about 23-25 dice, well that's fairly easy, my werewolf can drop 47 at 9-again and rote, but that's ridiculous and also because he's 'twinked' in that specific area. That being said, I make it abundantly clear to any new, or existing ST, what my character is capable of, and then I work with them to deal with things, and if there are new players, I really encourage them to express and expand upon their limits to see what they can do. I honestly don't want to hog a scene unless it's specifically for me (Aka sojourning through deep Shadow to go steal something from a rank 5 spirit) then you better believe I will play to all my character's strengths. But little combats, there's no need to show off, let the new guys have a crack, save their asses so they survive another day if things get out of hand, but don't steal the limelight when it isn't your turn. It's all about being respectful to other people and players.
So, hopefully that helps a little? I realize I've hit several nails with this post