Not sure if that's possible since that bar also indicates durability and changes color when it's less than 100%. The two might conflict with each other (not that we need the color change for durability since the bar size indicates when it's getting low).

I use Materia Extraction on the Actions & Traits General menu when I want to check spiritbond. It's set up in groups like Repair but it will sort in order of spiritbond so any thing ready for extraction is at the top of the list. I can quickly search for any items on my character ready for extraction this way, and I don't run the risk of accidentally selecting Retrieve instead of Extract from a submenu. It's a lot of convenience for a single extra button press.