I think that, unlike the T20 Blast and other innovations over the past 50 years, there was a clear understanding that these would support the county game. Even the coloured clothing, mascots etc associated with them do try to develop an identity that appeals to supporters beyond the county stalwarts.
Whilst The Hundred is also justified in the same way, the plain fact is that the noticeably smaller number of teams taking players away from the county circuit is bad because of the moronic idea that non-cricket people are more likely to identify with a city rather than a county.