Though you're completely right - much more than 12 size level on 167 ppi devices (and maybe 16 on 300 ppi) really don't make much sense. A scaling fine enough is more a problem, therefore the 14 steps for all resolutions are a good compromise. Unfortunately, the defaults choosen by Amazon are nothing less than a PITA, especially the way to giant last 5 steps... but a personal FONT_RAMP file helps.
