The rich won't moan about paying an additional 10% in price but about having to pay more because they are foreigners.
Somehow this is not in line with beeing an investment friendly and easy to do business country.
Any investor, whether property or in setting up a business likes stability and transparancy and by suddenly changing such rules to the detriment of foreigners will make some nervous of the possible manipulation that can hamper investment returns.
Changing EP and Dependant's Pass fees, for example, from $30/yr to $120/issue was the starting point for showing protectionist policies.
Now that SG has officially overtaken HK in expense, the timing of this additional stamp duty is a smack in the face to FDI.