Bedrockgames
I post in the voice of Christopher Walken
But, by having mechanics the will automatically sideline your character, you are baking "rationing fun" into the mechanics. Take a poster child here - 3e rogue sneak attack.
Now, from a believability perspective, it makes perfect sense that your rogue can't sneak certain creatures. Fair enough. But, that means that there will be significant periods of time when your rogue character's effectiveness is hugely reduced - to the point where you aren't really doing much of anything - sorry, d6+2 points of damage once per round vs a CR 8 creature isn't really doing a whole lot.
Now, you didn't choose this. You had absolutely no say in this, other than the fact that you chose to play this class. The DM decided what creatures to use and the game designers decided that you're not tall enough for this ride.
To me, that's a poster child for mechanics that are not as good as they could be. If the rogue player chose to be less effective against certain opponents in exchange for something else, then fair enough. That's on him. But, he didn't have that choice. It was baked right into the class.
Now, it might not come up for several sessions. No worries. But, then you have a four hour session where you have five encounters in a row with undead (for example - maybe a zombie horde is attacking). The rogue player just got benched for virtually the entire session through no choice of his own.
How much is that "verisimitude" worth? Is it worth having someone ride the pines for four hours? To me, the answer is a resounding NO. Not being able to do a lot in a given encounter? Ok, that happens. Not a big deal. I have a character that just doesn't have the skill set to really contribute to this particular scenario. Cool, no worries. But the mechanics should never sideline players for hours on end.
And that's what unbalanced mechanics do.
To me this is fun. There are going to be periods in the campaign where my particular thing isn't all that useful. It makes it that much cooler when I do shine. I get that this doesn't work for you, but that doesn't mean its bad design. It just isn't a style of play Hussar likes.
And this is a prodocut of choice, product of the most important choice a player makes: what class to play.
Lets also keep in mind, in most campaigna, the Gm is expected to consider the strengths and weaknesses of different party members. So more likely you will have one or two undead encounters but not the five (or there would be things thrown in there for the rogue to do at various stages----rogue might not be good at fighting undead, but he is pretty darn good at breaking into the vampire's lair and clearing traps). Personally that one five encounter game wouldn't bother me, but I realize in most campaigns that prefer this style the five encounters with undead wouldn't occur.
Also, in my mind, this player isn't doing nothing this entire time. He is still in the fight, just playing a minor support role more than anything else. A lot of people can handle that just fine for portions of a game or campaign because over the long haul it balances out.
I want it to matter which monsters the gm throws at me. If any given encounter is going to assure me the same amount of input and shine time, to me that is dull.