Without reliable global measures of readability, perhaps the best we can do (and the approach adopted in STOP) is to design messages that readability experts think are appropriate for poor readers; this is something that can be done in a single-solution pipeline architecture.
if we cannot properly measure the thing we are trying to optimize or satisfy (which may be the case with the majority of constraints and optimizations that today's NLG systems builders are concerned with), then there may be little value in shifting to a complex architecture that supports more sophisticated search (which is perhaps the main benefit of revision and multiple-solution pipelines).