Preference for basic conditions in ester hydrolysis
Precedent - why change conditions that others have shown work well? 
Control - it is much easier to react 1 eq of base/nucleophile under mild conditions, whereas acid hydroysis generally requires excess reagent and higher temperatures. 
Ease of operation - base hydrolysis gives a carboxylic salt as product which frequently extracts into aq, giving an easy workup and purification. Acid hydrolysis requires neutralisation of excess reagent as a first step.