Well if it breaks things, then that is a problem. 
However, I think that sending a list to 
[t l l l], and replicating the list to each output would have very few applications. I would like to see a patch where someone is using this feature. 
I've done that lots of times
 
Anyway, that is not my use case. 
My use case is 
a) literals in [t] not working the same between [pack] with similar looking syntax (as illustrated)
not a good point as both objects are supposed to be quite different, and each object has its own design or "syntax"
 
b) sending a list to [t f f f]. Distributing the list to each float seems rather useful
this task is performed by [unpack f f f] already. 
I don't really understand your use case, can you give us more details?
 
cheers