Different tastes.
Possibly, though all you've convinced me of so far is that Bob isn't very entertaining when he role plays and you still feel embarrassed when you do it.
My main point is anyway, that I strongly oppose any in game manipulation to try and get your players to play the way you [generalised] enjoy.
I oppose any strong armed in game manipulation, but I'm not sure that's the same thing. You have to cozen and seduce people in to playing your game by making it so fun for them that they don't remember they don't like to play this way. But if they aren't having fun, you can't make them have fun and you should shift your tactics.
No amount of spicing up NPCs or forcing their characters to talk will ever change that.
Maybe. Maybe not. But my main point is this; if I'm not having fun, in a couple of sessions I'm going to say, "I hate to say this, because it's been great to have a chance to play,but I've decided to shut down the campaign. I've got a lot of things going at work, and keeping up with this campaign takes a lot of time and I don't think I can keep doing it.", and what I'll be thinking is, "Go find some other poor schlob to abuse." If you staring at Bob eating nachos is boring, chances are its absolutely brutal for the DM. And at some point the tons of spreadsheets tracking income from taverns the rogue owns, trading income from your 30 sailing vessels, and taxes collected from the Paladin's fief gets likewise uninteresting sandbox or not. I mean, I enjoy creating 100 page random encounter tables as much as the next DM, but if I don't get something out of running the game I'm not going to run the game. There is only so long that killer death dungeons without interesting narratives and NPC interaction stays an interesting staple of play, and I got to tell you, that length of time is somewhat less than 30 years.
My feeling is that if you've played more than 20 or 30 sessions of D&D, as a simple point of pride in your skill as a player, you should be able to perform in and enjoy exploration play, tactical skirmish play, role play, mass combat play, investigative play, low drama soap opera stuff, high drama political intrigue, player centric problem solving, character centric problem solving, and so forth. Maybe one you enjoy more than another, and maybe you'd rather the focus of the game be on some and not others, but you ought to be trying to cultivate a taste for and skill at all of them. Beyond simply pride in being a 'good' player, you never know who you are going to start gaming with. The OP seems to have a problem where the game she wants to have is not one that her player's have the skill for. If you are the sort of person who only likes pepperoni pizza, and that's it - never mushrooms, onions, or anchovies - then you can only share a meal with other people who only like pepperoni pizza. If you are someone who sets out to cultivate a taste for every sort of topping, then regardless of what is being served you are going to enjoy it a least a little.
So sure, you don't have to enjoy green peppers as much as me, but if me having green peppers on the pizza makes it inedible for you, I'm not sure I would take pride in that.