Why would a standard solution of ethanoic acid not be suitable in an experiment involving hydrated Na2CO3?

When you carry out a titration, you rely on there being a rapid change in pH at the end point. If this occurs then the indicator will change colour within one or two drops being added from the burette. This is indeed the case in an acid/base titration if the combination is strong/strong, strong/weak or weak/strong. However, if the acid was ethanoic acid (weak) and the base was sodium carbonate (weak), there would only be a gradual change in pH around the end-point and the indicator would gradually change between its two colours over a range of several cm3 of the acid being added making the end point very indistinct. The problem is futher compounded by the fact that carbonate is a diprotic base (accepts 2 H+) so there will actually be two endpoints but both will rather indistinct when titrating with a weak acid.