This would totally ruin the game. it was 44k from 74 to 75. now imagine that 24 more times with always a higher amount of exp to reach per lvl up.
HNMs would be a total joke. lvl 90 mobs? what would that con when checking these on 99?
New gear would be needed. pimp gear would only be "something useful from 75 to 99".
The list of how much fail this is goes on and on, and in my opinion this would kill FFXI