What are the major pros of getting a PoE switch for WAPs vs just using power injectors?

I am going to add 2 WAPs to get 3 total and currently the one WAP is into our switch via power injector. Normally I would have a PoE capable switch but in this case I don't.

What are the compelling reasons to get a PoE switch and run the three WAPs off of that instead of just buying two more PoE injectors? I'm planning on using 802.1x on them.