From your link:
"LIBs have short lives (in comparison to NiCa batteries, etc). You should expect to buy a new battery in 2-3 years after being manufactured. It is caused by internal oxidation and there's nothing you can do to stop or prevent that.
Same goes to WiFi connection - although it's on, if there is no data flowing through it, it uses almost no energy"
Thus, in 3 years at the most we will be buying the Kindle Fire of that year. Also, leaving WiFi on all the time uses almost zero energy if we are not receiving or sending data.
That link also recommends a full TWELVE HOUR charge when first receiving one's LIB (Fire). Maybe those, who are getting low battery times until depeletion, should try an overnight charge to perk up their meters.