IR spots were really only needed for keeper or dynasty leagues in the past since there was no reason to hold onto a guy in a redraft league if he's done for the season.
I believe I read that the NFL is changing the IR list this year so that players can be put on it for a portion of the season - thus it will have relevance in redrafts too. If you have small benches, IR spots are good to have (1 or 2 at most) - in the case of larger benches it may not be necessary.
I suggest you throw it open to a league vote if you want to introduce it.
First off, thank you for the comments. Much appreciated.
Currently we have 10 teams in this league. There is a 50/50 it might grow to 12 teams by the weekend but that will be the max. Currently we have this roster setup:
1QB, 3WR, 2RB, 1TE, 1W/R/T, 1K, 1DEF, 7BENCH
So there is some depth on the bench. And truthfully I am not wanting to use the IR spot as a "true" IR spot since as you noted it's really designed for keeper leagues. I was wanting to use it more for week-to-week injuries where players are out for X time due to an injury but not technically placed on IR.
I have never used the IR spot in Yahoo to know if they restrict players to players designated IR by the NFL, or if the commish has control over who goes in the IR spot. If the commish has control then I can setup some rules and post them so all can agree and do this manually. If not, it's a waste like you said.
FWIW, I have talked with 80% of the managers and they are in favor of an IR spot if it can be used as I would like.