People are paranoid. If you've followed J-pop, Best albums lately have just meant they want a quick buck. They don't have to spend money making more music, just printing the CDs and promoting it. Best albums usually sell well, though they've lost their steam in 2006 after the over saturation of Best albums from VERY active artists.
34 or 35 singles or whatever, thats a great time to have a compilation like this. 17 songs on each CD, etc etc.
And those disbanded groups who've put out a best album in the past...that was AFTER they disbanded.