A crappy longbow and no mention of greater banes or slayer arrows isn't helping your case.
Not that I expect you to have greater banes and slayer arrows on 100% of the time, but they're pretty much required in a boss-beatdown scenario to remain competitive when manyshot is down.
Let's compare a level 14 horc barbarian to your numbers here:
20 Starting Str +3 levels +6 item +2 rage potion +6 Rage Str +2 ship buff +2 frenzy +2 horc enhancements +1 horc power rage +4 barb power rage
= 48 Str (+19 mod)
+5 Flaming Burst Greataxe of Pure Good
1d12 +5 enhancement +28 Str + 10 Power Attack +4 Horc PA +6 Barb PA +4 Orcish Melee Dmg = 63.5 base damage/swing
Give him bloodstone too. Note that Frenzied Berserker 2 gives him +1 crit multiplier on rolls of 19-20.
Miss (1): 0
Hit (2-18): 63.5 + 1d6 flaming +1d6 pure good +2d6 frenzy = 77.5
Crit (19-20): 254 + 24 bloodstone +1d6 flaming +1d6 pure good +2d6 frenzy +2d10 flaming burst = 303
That's 96.175 damage per swing.
Glancing blows:
At 12 we'll give him just THF, no iTHF or gTHF. That's 30% base damage, 7% special procs, on 2/4 swings.
19*(63.5*0.3 +2d6*0.07 + 2d6)*0.5/20
=12.6065
So that's an average of almost 109 damage per swing. At a hasted attack speed (99 attacks per 60 seconds) that's almost 180 DPS.
Well you've got about half the attack speed of a barbarian, so you're doing 40 to 60 damage per hit and 33 to 49 DPS. The barbarian is doing over 3.5 times your single-target DPS.
Not really, as shown above. One of the weakest melee classes at mid levels is a Frenzied Berserker. Most of the DPS gains are at low and high levels. So the best case scenario for you, your well-geared ranged character versus a well-geared melee is doing less than a 1/3rd of the DPS... best case for you, assuming your numbers are right. Of course this will change at higher levels but that's just at level 14.
Melee attack speed is about twice as fast as ranged, and scales much better using haste. My barbarian hits for over 100 per hit at level 20, and over 600 on a crit.
You're right, killing trash is easy because your damage is multiplied through several enemies. Trash killing is usually not too important, although it is valuable.
nah, it's just +25 damage per hit on average, a little less than a frenzied berserker gains from the greater vicious property that is applied to his weapons at level 18 (and not including the crit multiplier bonus he gains from it as well). 4d6 damage on all hits and glancing blows and +4 strength > slayer arrows during single target DPS situations.
It's true that ranged offers some utility for certain situations, but most of combat is still close quarters in DDO.
Your bow helps you in explorer areas, but I usually just sprint past those anyways. Certain spots also favor/require ranged, like getting Lailat in DQ2 off the wall. You also have amazing trash DPS if you can collect up a bunch of aggro from melee toons and manyshot + improved precise shot them all down. All in all, ranged are not 'gimp', but it isn't particularly strong where it counts: raid bosses.
But keep in mind that your single target DPS will always be much lower than a melee toon, and so when DPS truly matters, like beating down Horoth or finishing off an enraged Lailat, you'll be a liability in comparison to other toons.
Your problem is that your character gets very little at level 18, and the traditional 'tank-type' melee characters, the barbarians, kensei, paladins, and monk all get huge boosts for their tier 3 prestige.