It does, if its in addition to everything else, e.g. the plethora of tactical options that 4e offers:
E.g. once every attack roll must hit and then the opponent must also fail to parry and/or dodge, it means that more daily and encounter attack powers will fail. And this means that less damage is dealt overall, resulting in longer combats.
Of course, if 4e had been designed to take that opposed roll into account, they might have increased the average chance for an attack to hit to take that into account.
I've also been playing various roleplaying games for 25+ years and in general systems using multiple rolls to determine the result of an attack take longer (DSA, Earthdawn, Runequest, ...) unless the system's equivalent of hit points is a very small number (i.e. the system is pretty lethal since a single attack that actually connects and penetrates armor can result in death).