In dealing with questions like this, it's important to try and examine the terminology we use to describe military affairs. The work "phalanx" in particular deserves a fair amount of critical attention in light of recent developments in scholarship on Greek warfare, which is admirably covered by /u/iphikrates here. Personally, I am not of the opinion that "phalanx" is a useful term to describe medieval infantry tactics because the term is so confused even in the original Greek context.

More to the essential point of your question, the entire purpose of longbows was to weaken an enemy so that the heavy infantry could engage in an advantageous position. In the English context, these tactics were primarily defensive in nature. The goal was to lure the enemy into attacking, then disrupt their attack with missile fire and field fortifications so that waiting English men-at-arms could hold out even against superior numbers of the enemy. The longbow was not supposed to decide the battle on its own, but under the right commanders, experienced longbowmen made an excellent component of a combined arms force. English longbows were present in other forces that made more use of pikemen, such as the Burgundians. The French developed their own force of francs-archers (many of whom were likely English soldiers who had previously belonged to garrisons newly recaptured by the French) to support their reorganized companies of ordinance in the late 15th century.

There was recent discussion about this episode in this thread. /u/valkine provided the top-rated answer, but there were other contributors as well.