Well what would have made more sense was limiting Blade Cascade to solely a Blade Cascade special attack sans absolutely any other effects.
Blade Cascade, in and of itself, is not ridiculous. The problem is tossing in something like Imperiling Strike.
I don't know about everyone else, but in groups I've played with we find it fun and a great way to build dramatic tension and excitement if someone keeps making roll after roll. The group collectively stops what they're doing and becomes captivated by the result of the roll, that's what I thought they were originally "going for" in terms of BC.
They could have errata'd Blade Cascade to something like "You make a single attack with BC, ignoring all other modifiers to your attack rolls. Roll a d20, if you make a 11+ you hit regardless of AC/Defense/etc. If you hit in this way, you may continue to attack under the same conditions, if you miss BC ends."
I mean, I thought the intention of BC was to set up a fun "roll-fest" and see how many times the player can manage to make that 11+, not limiting it to 5 which is an entirely arbitrary convention. Why 5 and not 4 or 6 or 3 or 7? What's special about 5?
Stupid Wizards. My limited experience with 4th ed has been luke warm at best, and pulling random limitations out of their ass to a poorly play-tested product really grinds my gears.