As it stands, the court is the arbiter for whether a law (or section of a law) is legitimate and how it's applied. All this would do is remove the latency between legislation being written and it being 'tested'.
It probably wouldn't be practical, given that they currently don't review anywhere near 100% of legislation (but maybe that is a feature).
I would be concerned about the situation where the court effectively ends up with a veto and maybe decides that they should be the ones in charge. The only way out of that pickle is to reject the constitution.
