As a DM, I think I am a bit on the generous side. I give out treasure almost every session, but it is normally rolled from the random treasure tables from the DMG. And I give out XP based on the CRs in the book and for "roleplaying" if there was little combat during that session.
As a player, I hate waiting a "long" time to gain a level. I am not a munchkin, bad role-player, etc. I see DnD as a game I play to have fun.
Speaking for myself, a big part of that fun is seeing my character continously grow, which is done by gaining levels as well as reaching story goals, etc.
I played in a game where it took 2 years to gain 4 levels, which for me was really slow. A fellow player at the table only gained 2 levels because he died twice during the game. Lucky for me I didn't die during those 2 years.
They way I see it, I don't want to invest a few YEARS of my life gaining in return 1 or 2 levels. For some people, that is perfectly acceptable and fine. More power to you. For me, I have other things I want to accomplish in the game, which is inherently tied to the level a character is at.
I have other things I want to do with my time than playing in a campaign, hoping to see some of my goals reach fruition, but then realize that at the rate I am going, it will take literally half-a-decade to get there.
For me, that's a bit too long, even if it's a game I love.