You must be talking about several years ago - not to long ago leveling was much faster than it is currently.
I'm not sure what to make of the rest of your post... did you ask a question? 
Goblin Caves, Gorge, Luna, and Oblivion Temple are all ghost towns because through out that entire level range you can get better exp in DoD.
I think the biggest difference in what you are talking about - is just the various stages that an online rpg goes through. Early on in it's life people still use the content in the early levels - once it is established the content focus shifts to late game or end game.
The meaning or importance of having a high level character is only significant in the early stages of a game's life. Sorry - but I don't think there is anything you can do to get that back 
^
This, in the beginning or beta versions of mmorps the game will be fun because there are lots of people playing ( given its fun gameplay and no constant DC), some even just visit beta's then leave never to try the game again. There are maps/kings to explore, items and skill to learn it all seems so much. Then after some years most thing have been tried and done. So the new feeling vanishes and late game stuff becomes more important.
Still some people keep lvln at dod from 90-160 which I dont understand, they miss half the game playing in that map, dont get drops for the a big part of their lvln to 215 and dont realize that oblivion temple quests and MCs in luna temple give good exp as well. 70s lvls in the same map, yay thats alot of fun >.<, true its nice exp, but past 130-140 you should really move on. Then when they exit they dod style lvln and dont know about MC or OT or prison for that matter... lol they cry that lvln past 150 is sooo slow.
I do feel they maybe could change something to merit lvln in luna again, as atm its just deserted. Only people I see there are farmers/ lost people/ loners looking for the meager scraps of exp. Luna Temple MC's are nice but that leaves out alot of maps that are almost empty.
The same exp thing in parties did make it easier to lvl but they could always just tune down the exp gain from monsters... In a way it did help parties as before that you had to wait and hope someone would party you and found you to be skilled enough/ good equip to merit entry, otherwise you would just slow the lvln down.
On her question of how you keep the boredom away
well sometimes you don't and just log off. Maybe start a dif char, set yourself a goal for a certain item/unique, make noobs to lvl to 50 on kings then delete them. You could gear all your noobs in leg armor with good subs if you just keep it up. Do union wars, do union quest, do the quests in general and actually read the story line to follow whats happening on all the planets. The fate quest is nice for this, so are all the second job quest texts but this ofcourse only works once.
