In truth, it's more complicated than that. Please do keep in mind that the following is the observations of someone who has filed one full-on patent and several provisional patent applications in the past.
It's more like 14 years from the grant date for a design patent and 20 years for a utility or plant one.
There may be an offset to the drop-dead date given to Pharma based patents that Congress gives per statute where they offset the time spent in government testing so that they effectively have protection during the testing phases and then have the 14-20 years from the moment it's approved forward.
Patents are not renewable at the end of the term or under any of the other expiry situations that are present with them. As alluded to in the previous paragraph, they can be extended in some selected special cases. There is a maintenance feel that is owed during the duration of the life of the patent on a regular basis (about every 3 years...)- if you don't pay up, the patent expires. It's presumed that if you're not paying the maintenance fee, you're no longer interested in maintaining the monopoly it grants you for whatever reasons.
For most things, the story is 20 years from the date that it is granted. You can't use patented or patent pending on things that don't have a patent application pending or granted on a given thing. You have no protections in the normal sense of things if you don't have the patent granted- "patent pending" is truthfully of limited use, other than warning people that they may get cut off (if you can't prove proof of prior art preceding the patent application, you can be deemed to be infringing the moment the patent is granted...).
Now, this doesn't get into obviousness, patentability of software, prior art, etc. Each of these can invalidate a patent out of the gate. The big problem is how expensive it is litigating anything in the patent space- on either side of that courtroom. A patent is only worth the amount of money you can litigate it over. Trying to bust patents is only going to go as far as you've got deep pockets to fund that endeavor.
Does it need to change? YES. Not in terms, but in more what IS and ISN'T acceptable and lower the bar to entry to invalidate obviously incorrectly granted patents.
I understand what you're getting at and I agree if it involves a magic cancer cure, the GUI, etc... but this patent solely patents using floating points in devices that do 3D computations and have framebuffers. That is like patenting integers! Absolutely rediculous! This does not took more than literaly 3 seconds of 'research' whatsoever.