Honeslty I don't have an issue with hawkshot, and I like her kit the way it is, though I do feel she is underpowered, mostly in laning phase.
Her weakness in laning phase comes from a few factors:
Her W cooldown at early rankes is pretty insane, 16s to 4s from 1 to 5. That 16 second window without having a spell to trade is quite significant.
Her Mana pool is TRASH. 173+35/lvl, worst in the game for ADC's with the exception of Jinx, who is mana gated since her spells are quite powerful, and she gets a lot of power from her manaless Q form.) Ashe starts with enough mana for 3 volleys and 3 frostshots. Basically her volley is both mana gated and cooldown gated. In most cases, ashe starts with around 60 less mana than a typical ADC.
Using frostshots (8mana/shot) and a few volley's OOMs her in lane when she's trading. Not to mention making it to level 6 with 100 mana to ult.
I feel like a caitlyn comparison is needed to put this in perspective:
Mana Pools + Regen
Ashe: 173+35/lvl mana (6.3+.04/lvl)mana/5s
Cait: 255+35/vl mana (6.5 + .55/lvl)mana/5s
Spells
Piltover:
COST: 50 / 60 / 70 / 80 / 90 MANA
COOLDOWN: 10 / 9 / 8 / 7 / 6
PHYSICAL DAMAGE: 20 / 60 / 100 / 140 / 180 (+ 130% AD)
MINIMUM DAMAGE: 10 / 30 / 50 / 70 / 90 (+ 65% AD)
Volley:
COST: 60 MANA
COOLDOWN: 16 / 13 / 10 / 7 / 4
PHYSICAL DAMAGE PER ARROW: 40 / 50 / 60 / 70 / 80 (+ 100% AD)
I doubt anyone will argue early game volley is as good as Piltover... It does less damage, it can be entirely blocked by minions, its mana cost is similar (from a smaller pool,) and it's worse for pushing.
Frostshots also mana gate ashe, when really the only thing ashe does asside from shoot giant ice arrows is apply frostshots and kite stuff.
Volley isn't really much of a damage spell, it rapidly decays into an autoattack interupt that applies frostshots, rather than a real damage ability.
Ashe is basically a DOTA champion that is in League of Legends from before the game fround its style.
My suggestion:
~Remove the mana cost from frostshots and make it a permenently applied passive, so Ashe doesn't go OOM from doing the only thing she does, kite stuff and doesn't have that annoying and unresponsive toggle.
~Reduce early cooldown of Volley to 10 to 12 seconds, rank 5 cooldown remains 4s. Consider scaling mana cost 40 to 70-80 mana
~Increase mana pool or reduce cost of Enchanted Crystal Arrow
~Consider allowing Volley to crit if late game power needs adjustment.