Why is Mercury considered a planet when Pluto is not?

I still remember my initial thoughts when they demoted Pluto to a sub-planet a few years ago and declared that our Solar System now consists of 8 planets instead of 9. WTF? It was just a frozen rock anyway, but if they are going to do that, why not remove Mercury, as well? I mean, there are freakin' moons bigger than Mercury! Yeah, we'll just say our Solar System has 7 planets, instead. Personally, I liked the way it was before all of this sub-planet babble. Update: Now they call such things a "dwarf planet," but a name change still didn't bring its original planetary status back. ---End of Update

The reason why I'm picking on planet Mercury, is because it is just a tiny, hot, barren, dry, airless rock with a gravitational pull so weak it can't even retain an atmosphere! Yeah, this is one cool planet, eh? The scientific community still claim that, unlike Pluto, this miniature 1st rock from the sun still meets all the requirements to be considered a planet. Either way, it would be a terrible place to hang out. It has the biggest temperature differential than any other planet in our Solar System. I've read that a year on Mercury is only 88 Earth days. This little rocky "planet" acts more like a punching bag for various types of meteors and comets, by looking at the surface. Actually, it looks more like a beaten down moon that somebody lost; ha!

Side Note: The 3 main requirements by the International Astronomical Union to be considered a full-sized planet are: 

1) It is in an orbit around the sun. Duh! I mean, who would have thought? Ha! 

2) It has sufficient mass to assume hydrostatic equilibrium. Without using all of the scientific jargon, this basically means that the end result of the formation of a planetary body will be somewhat spherical. Yeah, I wasn't searching for floating celestial bodies in the form of rectangles or triangles, but I guess they need to have some standards.

3) It has “cleared the neighborhood” around its orbit. This is what is considered to be the main reason that Pluto is no longer a planet and is considered a dwarf planet, etc. If you are wondering what could possibly be in Pluto's 'hood that is so bad that they stripped it of planetary status, then blame the Kuiper belt objects such as the "plutinos" for contaminating its orbit. Sounds silly, right? I mean, who wants to hang out near Mercury? So, who cares that Pluto has little friends? Well, I guess the IAU does...

The bottom line: If you are going to pick on Pluto for being a frigid rock that only serves frozen doughnuts to the galactic space cops, why not give Mercury a few good kicks to the groin while you're at it? LOL!

Image Credit: This file is in the public domain because it was solely created by NASA.

---End of Post "Why is Mercury considered a planet when Pluto is not?"