I always liked the idea that even if i am caught with my pants down i could still summon a full suit of armor and a weapon on the spot.
Did wonders for my role playing experience.
But being an archer summoning a bow didn't do much for me without some arrows.
A good mage can do everything without any need for gear : fight , heal , open locks , ...
I think it would be fair to give as pure archers ability to summon our own ammo (arrows) if we are given a summoned bow already.
( we do need to burn some of our mana from our tiny mana pools to summon them so it does cost as just as a mage needs to burn some mana to cast a fireball )
Something like "summon Daedric Bow + 25x Daedric Arrow for 3 minutes"
(and it really should be 3 min , not 15 s like Oblivion gave us )
I know that many would want this but apparently if messes with the new archery (a small number of arrows) balance thing.
And i so don't care...