Neither would i, but they would certainly be better achieved on a 7" than a 3.5", just like those things would be better done on a 11" mba than a 9" iPad. Theres a tradeoff to everything. 9" trades of portability for use. 3.5" trades of use for portability. 7" would be no different. Still, it would do some things better than the 3.5", and provide higher portability than the 9". I really don't get the problem here. The 7" has a clear use case on its own, a use case neither the 3.5" nor the 9" can really fill. Especially not when taking other devices into consideration (e.g. a laptop already in the bag).
I personally don't see how 7.x" device would be that much more portable than existing 9.7" device. Even if you are running with this all day
it will feel pretty heavy at the end of the day.
And, even if 10" is the better size, that in itself is no reason not to offer the second-best size too. Evidently, iMacs come in different sizes, MacBook pros and airs too. Why need this be any different?
Because difference between 21.5" and 27" iMac is much smaller than difference between 9.7" and 7.x".
if it makes sense to make a smaller iPad it should make sense making a smaller Air too for example. Apple hasn't and won't be doing that.