You, person whining about how passive talents are boring, please shut up. About that specific subject, not in general. Passive talents are exciting. EXCITING!
Let's walk through things a bit. Here is a level 51 rogue. What does he have going for the next level? Well let's see... nothing. Next? Nothing. Only at level 54 does he get envenom. Woo! Excitement! In... three levels.
Now let's give him a Terribly Boring Passive Talents-Filled Talent Tree (TBPTFTT). Next level he can... well actually I'm not sure what talent he'd take at level 42 because the trees already got butchered. So let's say he's combat and will get Improved Sinister Strike for 4% damage to sinister strike, a terribly boring passive talent that I just made up and which he took after having picked up the 31 point talent which was exciting: Super Sinister Strike, which is like Sinister Strike, but it does more damage and adds a buff to increase his Sinister Strike damage by 25% for 20 seconds, with a three minute cooldown, which because it is a button makes it Fun & Exciting. In time he can get an entire 5 points for a total of +20% damage to Sinister Strike which leads into Even Better Sinister Strike which causes his Sinister Strike to have a chance (Ooh, no stated chance! I bet it's a PPM! Quick, theorycraft the slow weapons! Or maybe fast! What is the poison mechanic this week?) to reset the cooldown on Super Sinister Strike and also Improve Sinister Strike will now apply to Super Sinister Strike.
In other words, he hits level 42 and presses another button. Wee. WEE! INDEED!
That added button makes level 42 just a little bit more rewarding and eagerly anticipated. And level 44 too! With this boring passive talent he now has something to look forward to for level 42. It's not a big thing, but it is something. Contrast this with the typical nothing. Now what is boring? Yea, NOTHING. Nothing, outside of philosophy, is pretty fucking boring.
The boring passive talent isn't just a button. It's also a tantalizing possibility. Now there is that box that says 1/5 Improved Sinister Strike increases the damage of Sinister Strike by 4% and if you mouse over it also says that 2/5 would increase it by 10%. Right there, that is room for growth. Oh man, 2/5 is on its way. And then 46, that's 3/5! 48 gives 4/5. And then... oh shit, it's level 50! Ooh, side-track time to get that sweet 40 point talent (note that there may not actually be a sweet level 40 talent, if not, shift things up or down by 10 levels and you'll find one). But level 52, bam, box is filled up with a 5/5 and now he can see that Even Better Sinister Strike is at an empty 0/2. Looks like he has a plan for level 54 and 56. Sweet. Who knows what 58 will be, but damn, it's only going to be one point before level 60 and we know level 60 is going to ROCK.
But leveling ends and now... Now he's just a level 85. Or 97, whatever the level cap is for MoP. Now he's filled up his tree and there's nothing left. He can respec. And now, well now those passive abilities are pretty damn boring. Woop-dee-doo, 4% damage to Sinister Strike. Who fucking cares? On the other hand, Super Sinister Strike... also, who fucking cares? He's now making exciting choices anymore. He's picking the talents that he's supposed to have. There aren't going to be any exciting talents because there is no more advancement and no choice. Blame the level cap and excessive optimization, not the TBPTFTT. You thought I wasn't going to get to use that. Idiot.
"But," you say, "we have MoP now and we don't have all those silly talents. We have Fun & Exciting choices." Like hell you do.