Another way to look at this would be to consider how common the situation is where:
A) The rim is damaged so badly that it won't hold air while tubeless.
B) But not quite damaged so badly that it's dangerous to ride.
I think this exact situation is going to be pretty rare -- I've seen some pretty banged-up rims holding air just fine. Anything worse, or bad enough to start leaking, and the aluminum would likely be cracked and/or the tire would be badly damaged. And you'd be walking anyway.
In sum, an "ideal" in-between situation like this is rare and most likely not worth the bulk and weight of carrying a set of tubes.
2002 Suzuki DL1000 V-Strom, Dark Metallic Space Blue
1983 Suzuki GS850G, Cosmic Blue
2005 KLR685, Aztec Red - Turd II.2, the ReReTurdening