I must admit - I'm sort of surprised that the reputation decay hasn't caused an uproar as big as the 10% module sell penalty did.
Perhaps it is because it is more subtle, and as such some people didn't notice this yet. If this is the case, I expect more and more people will be upset as they discover their alliances wane and falter for reasons as silly as "I went on holiday"...
I am also surprised by this, as I was surprised by the uproar about the 10%, which I found rather logical and had always been expecting anyway.
Part of the reason why rep decay doesn't get nearly as vocally critisized is that lots of people, especially those who rarely or never visit the forums, are not even sure what is going on when they see lots of red arrows. There have probably been more posts reporting what they perceive as a bug where they mysteriously lost reputation, possibly randomly correlating with whatever they did around the time the next rep decay tick happened, than post discussing the actual game mechanic that is going on.
FD didn't even implemented the changes (major faction only etc) that they announced during the powerplay beta, that came in one of the minor updates later, and still it didn't get much forum attention.
Another part of the reason is that the consequences of reputation are more subtle, and only kick in at the milestones. As long as rep is still decaying through the buffer someone has accrued beyond the threshold for "Allied", they still get all the missions, repair discounts etc. And even when it has finally dropped down to friendly, these effects still remain subtle, and not everyone may immediately notice how they suddenly get worse missions and have to pay more for repairs. Plus, lots of people possibly don't really care about reputation beyond "get rep and naval rank for Dropship/Courier/Clipper".
- Major factions reputation is not important/vital to anything in game
- Missions require minor faction reputation
Missions require effective reputation. If a minor faction is neutral but its major faction is allied, you still get the missions for allied. We are not really allied with all these minor factions individually; go to a system you have never been too, and see three allied minor factions because they belong to an allied major faction - when the major faction drops to friendly, those minor factions will show up as friendly now, too.