Welcome to the forums.
The short answer is that the Nexus tablet is a Google device. Google tends to deliver that latest and greatest to its own devices first. There are no middle men (manufacturers and service providers) to deal with.
With the Optimus, you have LG and then your service provider to deal with. Ginger bread was the version of Android that a lot of devices had at the time of your phones realese. Unfortunately, service providers, especially verizon, slow the implementation of the latest firmware versions. They take forever filling the firmware with their bloatware.
The other "bad" point to note, is that manufactures and service providers are in the market to sell devices. They really couldn't careless that your phone doesn't have the latest firmware. Most devices only see 1 firmware update in their lifetime, 2 if your lucky.
Not sure about your technical savvy, but you might want to look into replacement Roms. Some developers will keep a device running long past the time the the manufacturers have written it off.
No guarantee that there are any available, it all depends on how popular the device is.
Hope this helps.
Looks like the zip doesn't have the power. Sorry