The irony is that this policy is not widely known within ICA, or even among services that dabble in the sensitive matters such as Intelligence, Law etc. Even know of a Perm Sec that wrongly advised a singaporean family friend who migrated.
The brain drain is serious. Something had to give. Its a practical approach and the whole world is moving towards it. Australia which had explicit laws on prohibiting dual citizenshiponly removed it in 2004. Singapore never had such laws but the official line was that it was frowned upon.
As to Singapore requiring foreign nationals taking up its citizenship to renounce their previous citizenship is to obtain a serious level of commitment to their new country. Its actually no big deal as countries like China and even OZ, allow one chance to reclaim back your previously renounced citizenship.
There many well known singaporeans that hold more than one citizenship. Its was the business community that first lobbied this as they are unable to purchase land or get into certain businesses without obtaining that country's citizenship. Rupert Murdoch renounced his OZ citizenship as US laws prohibited ownership of media by non-citizens. He was the one who lobbied John Howard to allow one chance to reclaim a previously renounced citizenship and he got it back. He nows hold 2.
Anyway, old man himself made a comment in the press circa 2007, that dual citizenship matter had been presented to the cabinet and for the moment kept on the backburner. I believe, the Population Secretariat is collecting stats before a final decision on publicising is taken. I believe it will include the one chance option for those that wish to reclaim their previously renounced citizenship without renouncing the citizenship of their new country. Reimbursing CPF funds is likely to be factor. It will favour business folks and scholars and students that remained overseas as they would have minimal CPF and are prepared to cough it up.