So just to reiterate some things and maybe draw it back to more specific bullet points of why a lower level cap is (we believe) better for the game:
# We want each level to feel like a significant boost in power.
# We want level benefits to be as clear as possible. Some people have suggested Well, let us hit level 60, but then keep giving us points after that. which isnt a solution, its the same problem except worse because theres no actual tracking mechanism built in (ie levels). We also want to avoid providing level benefits at irregular intervals (although this may be unavoidable for trait points), as some people suggest Let us level to 99 and just give us the rewards every few levels. This goes back to the first point: We want each level to feel like a significant boost in power. Trait points may not come every level, but the sum of the other increases from leveling, we feel, are still very significant and maintain our intent.
# Because of the extreme leveling curve in Diablo II, balance really couldnt be adjusted around level 99 characters.
# We can have long term status symbols people can go for that are extremely visual, show to others the effort youve put in, but not attach that to something like a character level. Along with artisans, achievements, gems, runestones, and all the other various character customization progressions, we still have some surprises left in store on this front.
The real bottom line is that we understand people like having those long term goals, and those feel good to chase and eventually achieve, but we do not feel one needs to be character level, and in fact making character levels a long term goal brings a great many negative effects with them (keeping in mind our goals for how important each level should feel).