Firstly , I think FDs in Malaysia is not an alternative to FDs in Singapore. Common concern is long term potential depreciation and rightfully so. To buy just for short term higher yield is Wrong. Buying FDs in Malaysia is best backed by reasons.
I bought MYR FDs recently and some of my reasons that make it very easy to implement...
a) Business dealings or rental income in RM.
b) Investment in Malaysia to create another Option - eg. allowing other assets of higher values to create yield and bringing you more passive income.
c) Ringitt is a currency you and your family can utilise frequently to exchange for a wide goods and services which you would otherwise need to obtain elsewhere (and at a much higher price) anyway.
d) You are able to size your position such that the weaker the Ringitt, the more passive income/free money you will have. Thus the need not to over-invest.
e) You are in a position/a reason to hold RM FDs for a long period (in line with (d), just a very small percentage) without the need to convert back to SGD because you have good use of the currency (in line with (c)).