It would be the same issue regardless the problem is not the exp its the lack of content.

Lets say they change it and make it slower. instead of 1-2days people would be doing it and 5-7 days. instead of 1 month it would be 2 months. the only thing that will change is the time they max out. Just because it takes more time to hit max will not increase the life of the game. Why? There will still be no content for them to do once they get to the end. so you are putting in much more effort for virtually the same thing. no matter how slow you level or how fast you level. without content to do the whole idea is pointless.