Would it not be better to make the maximum decimals allowed for a numeric field a configurable item to allow the administrator to decide what is a reasonable in the context of the application.
After all, everyone has different needs..
While there is a workaround it is quite cumbersome and not explicitly supported. An alternative method of multiplying the value by a factor to move the decimal point (eg pi = 31415.9265359 / 10000) is a sure fire way to get input errors
See thread below for proposed workaround using mds SPs and a further issue with the way numeric datatypes are defined