In regards to how level is right now:
1. It's more of an even spread of experience atm. Like, the exp per level gradually increases across all levels.
2. You can easily find the formula for the exp table so I might as well reveal what it is: 0.1*(level)^2 in units of billions of exp (except for level 1, it's just 0 exp instead of 10m). So, with that, it's a parabolic increase that's spread out through 100.
3. We felt that this was a fair system as it gives you plenty of levels and requires a bit of time. Don't forget the experience includes all the bonuses you get.
4. Speaking of bonuses, you're forgetting bonus exp from events, mobs, and bosses that will be released. These can give a massive boost to your exp for some effort. It's another way instead of grinding for hours a day.
Issues I believe you see:
It takes far too long for levels. I know what you mean as it gets to billions somewhat fast and there's just so many levels. The thing is, we could add more levels making exp for levels less with more levels and lessen the reward for leveling. 100 levels seemed like a fair upper limit for the people already level 80+ (don't forget Jerry DB is level 93). We didn't feel like making a game and rewarding the people with "YOU HAVE REACHED THE MAXIMUM LEVEL!" We have to balance things between all.
So, the idea is, do you guys want more levels requiring less exp or stay as it is and wait for bonus exp to REALLY kick in?
EDIT: I'm making a list for exp differences to help show what I'm talking about