If supplicating to Allah through a Wasilah is superior in terms of having the Du'a being accepted, does that make supplicating to Allah directly redundant in the Shi'a belief?
Bismillah
Thank you for your question. Not at all. Praying through the wasilah of the Infallibles (as) is a direct prayer to God. The form it takes is to ask Allah by the honor of that wasilah in His eyes. So one may take the Quran as a wasilah, or the Kaba or a prophet and so on. It is perfectly fine for someone to pray without asking by the right of a wasilah.
May you always be successful.