I'm one of those with a guild level in the 70's that are not happy with the system.
While the rate of bennies is much lower after 70, three are still substantial bennies. Better XP shrines for example. For my guild, the biggest one is getting to 85 and a larger ship so there are enough slots for sonic resistence and a stone of change.
In my guild of 77 or so accounts, there are 15 accounts that generate that vast majority of the reknown. The others are casuals, or come and go, generating at a high rate for bit and then disappearing for a couple of weeks due to RL. If I cherry picked the top 20 and kicked everyone else, we would easily be level 100 by now. That's not what our guild stands for, so we DON'T KICK based on reknown decay. We are cautios with new members though, as I am unwilling to further punish the 15 actives by taking on someone who might stop playing or switch guilds in a few weeks.
The 15 or so very actives are reminded by every guild level announcement of a small guild getting level 80 that they personally are contributing enough to sustain a level 100 guild, not a level 77 guild. Then events like Mabar come along, and we loose a full guild level because there is no reknown in the event and most of our actives are working on gear for alts.
Everyone, including me tends to break down the reknown decay to a figure per active account. That figure is roughly 1100/active account/day for my guild. But the reality is that the very active accounts have to cover 45K+ decay each day before we can make any progress. My family is 3 of those 15 very active accounts, so if we are traveling for a weekend it can take a couple of weeks of the entire guilds contributions to make up for that lost time.
That's why I hate the system. Not necessarily the concept of decay, but the reality of how the current decay system works.