Because my experience with renting apartments was that rates will go up at every renewal - don't like it? Move.
I could rent a new construction 2 bedroom luxury apartment in midtown Atlanta and pay about 1250/month in 2011 (I did this several times with buddies) - usually between 1200 and 1400 sqft. Now you can only rent much older units (constructed 70s to 90s) usually 1 bedroom or a loft for that price - usually around 900sqft.
I just searched the area I used to live for anything with 2 bedroom for 1250 and below. There is one result, and it's old student housing.
If I wanted a comparable apartment to something I could rent 10 years ago for 1250, most options now start at 2500.
Now - home prices have also spiked in my area, but the population growth doesn't seem to be slowing at all, and if I buy I'm no longer subject to yearly increases, and the perils of the rental market continuing to heat up.
Basically - owning means I get to still live where I am after the gentrification occurs. Because as a renter I'll likely be pushed out of the area (even if renting still is cheaper somewhere else in the city)