I personally continue to maintain that a slower leveling pace would give less incentive for people to make choices based solely on how much XP they will be getting.
I'm inclined to disagree with you on that. I don't believe that any amount of throttling of the leveling pace will stop people who want to gain xp and level over everything else from finding the best way of doing so and capitalizing on it. It might slow them down, sure. But if that's what someone wants to do with their game time that's what they're gonna do with it ya know?
Similarly, if less rp xp was given, do you think the people that play purely for the rp of the game would rp any less? Or if it was harder to make gold the people who like to become absurdly wealthy wouldn't still find the best way to make gold and make as much as they could off it?
Well, you're right in that some people will always try to place XP before anything else. And in the end - that's okay, as long as they play by the rules.
However, there's a large grey ground between the extremes of "always puts XP before anything else" and "never thinks of XP at all". I'd claim that most players are roughly in the middle of those two extremes; Perhaps even slightly towards the "never thinks of XP at all" end of the spectrum.
All the game mechanical systems cater to this middle ground from the XP cap to Exhaustion to needing to eat to regain more health by resting. People bent on not RP'ing these things can never be forced to RP them, and people bent to RP'ing all the nuances of their characters would RP them anyway. But for the people in the middle of this spectrum of the two extremes, we give incentive to do things in a way which - at least so we hope - increases the immersion for everyone.
When I'm talking about giving less incentive to push XP before other things, I'm not talking about stopping the people bent on maximizing their XP-per-playing-hour. I'm talking about pushing the people in the middle of these two extremes to put other things before XP just slightly more often. I'm talking about giving a few people more the push to go and think "Wait, would my character actually do this, or am I just doing this for the XP of it?" and I'm talking about slightly prolonging the time spent in roughly the same levels for those who dungeon several times a day and those who do not.
In no way is there anything catastrophic in the current situation, nor would I want to make dungeoneering an unrewarding experience. I merely think that a slight adjustment to making the cap stronger at lower levels would be nice, without slowing down the current leveling pace of those who are already slightly behind the average pace.