In an update on the WrestleMania 30 location, the early candidates right now are Los Angeles, CA and Madison Square Garden in New York City. In recent years, WWE has outgrown arenas for WrestleMania and have been running the event in stadiums.
The idea with holding the event at MSG is they've held WrestleMania 1, 10 and 20 at the arena so some within the company are pushing to continue that 10-year tradition. The plan would be to jack up ticket prices to an "insane" amount", knowing they'd still sell out the arena and would profit off a huge gate due to the ticket prices being so high.
The downside to running MSG would put WrestleMania in the same market two years in a row. That's not really something they want to do.