Hmm, maybe people are using these things in a way that was not envisaged, but I can promise you that your Palace reappearing when your Capital is lost was intended. If it didn't how would you calcualte distance calculations for corruption and culture flip chances? Also, where would you trade goods to and from with other Civs, and where would build the Spaceship?
The RCP (equal corruption at equal distances) could in no way be accidental. Maybe it was lazy programming (it was easier to take the loweset rank rather than the average of all cities at same distance), and maybe they thought that the consequences would not be huge to anyone that used this feature. At the very least I can say that it is not a "bug". That word is reserved for when your program does not work to specification, and I haven't read anything that says it should be the average rank.
But Aggie, consider the implications of 'banning' RCP. If I have 4 cities all distance 4.5 from my capital does that count as RCP? What it they are the best spots to settle? RCP doesn't even look to be very effective on 90% of maps due to the map specifics, banning it seems crazy to me.