Although I would rather see the price of NSR rise than receive dividends, the method of burning nushares instead of distributing dividends is risky.
The decision to buy or sell nushares from the open market will be known in advance and it would allow people to front run us and reap the benfit. For example, if a selfish nushareholder knows that NSR will soon be bought from the open market they would buy nushares and set a sell order at higher price.
What is more, if they knew that nushares will be sold on the open market to enforce the nubits peg a malicious nushareholder would dump their nushares on the open market. We cannot allow secrecy either because then the person responsible for buying/selling the nushares could abuse their power for their own good.
The same problem is actually with dividends too. If we know that peercoins will soon be distributed as dividends, speculators could try to pump the PPC price up prior to the dividend acquiring.
This has probably been discussed before somewhere in the forums but since I still see insights about seeing the NSR + NBT system as a whole, I suspect that such risks need more community attention.