I don’t know where this experience comes from, I find them strong, I used them on 3 different characters when they changed them. I tried all the elements, the character I use the most has an ice bow and a charged shot that freezes any small enemy. I beat all the bosses using the bow, and I didn’t find it any more difficult than doing so with a normal weapon.
Runes, on the other hand, as you said, are very weak, I talked about it in detail in a post I made some time ago: I really Like the new Bows but they are Not yet “Fully Cooked”
The Devs have already said that they will add Great bows (two-handed weapon), Crossbows and Great Crossbows (two-handed weapon).
Even though I am of the opinion that if they add the Great bows the current bow needs to be rebalanced to be a fast weapon, since it now has the stamina cost and attack speed of a heavy weapon, and so the Great bows can’t be even slower.