For an object in the solar system to be a planet, it have to pass certain criteria, such as being spherical. One of the criteria is having a gravitational pull strong enough to keep small objects to go into orbit around it, and this is the criteria that Pluto doesn't pass.
It's all a matter of definitions, and it doesn't change Pluto in any way. I find it strange that so many people are against calling it a dwarf planet. I mean, it's still there, it's not gonna go away because it's sad its no longer considered a planet by us