I don't think any animal should get a diet of 100% hard or 100% soft food.
Ellie gets soft food but also gets to crunch on raw vegetables all the time.
If I fed kibble, unless there was a serious medical issue that required me to only feed one food, I would definately feed soft food also.
Eating all hard or all soft food is just plain boring.
I say go for it.
Add the canned.
Ellie's vet and nutritionist are both fine with Ellie eating mostly soft food.
I see no problem with it and the moisture level is very good for her.