I remember reading a quote which goes something along the lines of "... They knew they were longbowmen by their twisted spines" - Skeletons recovered from HMS Victory (?) after it was bought back to surface.
There is already a nice balance between the fact that you could in effect loose a lot of arrows in a short space of time but you really wouldn't want to do it for very long because of the high strain it would put on you, hence the twisted spines (not surprising really).
By game balance, the longbow doesn't really have a niche, nor does it really scream to the best bow in the game. The warbow pretty solidly takes that plinth if I am honest with my outlook. All of the bows are pretty evenly spaced until it hits the longbow, I understand that the item balancers have their reasons for this although I would like to see a slight increase in the missile speed at the very least so that it has a bit more of an advantage and a desirable quality than higher damage and drastically reduced draw speed.
The longbows biggest flaw is certainly the fact that the draw time takes so long that you actually miss the "sweet spot" with your accuracy. By the time the game actually allows you to loose the arrow, your reticle has already bounced in and out, therefore making your shot more inaccurate. It's a pain in the arse and as far as I know, it's due to the low draw speed however as it was unusable many a patch ago when I originally petitions for a speed increase, this was much, much worse.
As far as I understand, it stems from the animations that we use, they are slower than the native ones given the same point ratings so 50 speed is the minimum (I found) to make the longbow at least, for the most part, usable.
The warbow, being 8 faster means that it safely misses this problem and allows you to hold your reticle for longer, because you have finished the animation before you're allowed to shoot.
I would say to bring the draw speed in line with the other bows but once again this would, in opinion, change the balance of bows again since the longbow, really, from what I see, is supposed to be a higher damage weapon at the cost of the speed.
The largest jump between an increase in damage and speed is between the tatar bow and the horn bow. You gain 2 damage (same as all other bows) at a penalty of 5 speed (as opposed to 3 in the rest)*** Maybe increasing the speed by 2 points would be a nice compromise for the longbow to (hopefully, not tested) kill off the unwanted "lag" between animation finish and reticle degredation.
This isn't really a massive compromise and won't be particularly noticable for the player base other than those who explicitly use the longbow and although it doesn't really address the issue that some people have that "it doesn't fit a niche anymore", it'll make it more viable by dealing with, what I think, is it's biggest bugbear.
Naturally, these are my opinions and they are biased, but I feel it's a reasonable compromise between actually buffing the bow to a state of supremecy and keeping it balanced.
*** Please note, I don't qualify the Yumi bow as a viable weapon and don't include it due to my biased opinion. That really does fit a niche market that doesn't seem to exist from what I have seen! :S
Also, I have nothing to with item balancing and I have little insight other than what everyone else sees, I just thought that I would share my opinion about it since I use the longbow no matter what.