1) With a lot of words about improving trust and safety in Proposal's summary, there is no evidence about issues with trust and safety with uncheked "abuse-c:"I've seen plenty of evidence and ramifications from first hand experience when abuse notifications go ignored/unanswered.
2) In my experience, real abusers have all their contacts valid (and responsive).
Please share more of your experiences. I've never heard of this claim nor understand what a "real abuser" is.
3) Why only abuse-c have to be checked? There are a lot of different contacts or information, that could be verified.
Because that's where you send abuse notifications. In many cases, these will be critical messages regarding ongoing threats, such as a denial of service attack or malware distribution.
Also, RIPE NCC executive just got extraordinary powers to revoke resource
False - no new powers are granted to RIPE NCC by this proposal.