Adding More To A Game Haphazardly Can Lead To Exploitation

I sometimes feel that Borderlands 2 has no (or little) notion of how numbers work and how numbers effect players' motivations. It comes across as though they just assumed that badass rank is something that the player will get over time. However you can find a way to just grind one of them and the rewards are so high for a slight increase in "challenges" that it makes the payoff hugely rewarding. For example, getting "second winds" with pistols gives you BR towards the "Hard Boiled" challenge:

2 seconds winds with pistols = 1 badass rank
another 3 SWs with pistols = another 5 BR
another 10 SWs with pistols = another 10 BR
another 15 SWs with pistols = another 50 BR
another 20 SWs with pistols = another 100 BR

see how ludicrous that gets? it goes from 0.5 BR per SW to 5.

I ended up running into Boom Bewm's lair, allowing constantly respawning psychos to kill me so I could then get my second wind on them. I don't think the designers intended for people to find a spot where they could "reliably get killed" over and over for the sake of gaining massive points but that's what ended up happening.

The second wind mechanics is something that always confused me too, so you're rewarded more for dying whilst nearly having killed an enemy more so than if you fully kill it?

But really I just wanted to show that if you add "more stuff" to a game then you need to make sure it isn't so exploitative. At least if you actually want to make something exploitative, make it a challenge to figure it out. What I don't want to see is more stuff being added under the assumption that it adds depth, because it may not actually be the case.

On a side note: In the menu screen, why does the EXP to level up display the total amount of EXP in numbers yet the corresponding bar only show the EXP within the current level?