The RC4 system has inherent issues that were documented in Jira, plus it also has a systematic risk to the network (Sporking is less risky than a hard fork, but there's a risk the network forks wouldn't actually go away when the spork was turned off after a failure). These few issues combined with the fact that we've reached 80-90% payment efficiency tells me that it's not worth the risk to the network to move from the RC3 payment system.
Also, I have a separate plan I've been considering as an alternative that carries no risk and can be done at RC5's launch. Basically, I would set a minimum protocol version and boot anyone not running RC4 or later off the network. This should get us to 98%+ payments.
why 98%+ and not 100%

Why

My take is that development on core features (anonymity) is far more important than enforcing the last 5-10% of MN payments. MN payment issues have halted development on anonymity for 2 months and we kind-of paid the price for it.
Any voluntary or semi-voluntary scheme of payments is crap anyway (trusted system), so it doesn't matter if it is 85-90-95 or 99%. It needs to be 100% / trustless / non-voluntary. That's as far as the long-run is concerned. For the short-term, relieving investor pressure from people acquiring MNs and expecting to generate income, it was the right choice.
+1
i agree, we have much bigger things to worry about
MN's are getting paid, sure i wish i was earning more,
but for the 'Greater Good' can /we should be able to live with it.
