Message me (Eustace) in game Aeillin and I'll explain to you why it would overpower rangers, from a ranger's perspective.
Back on the topic of ranger viability. Rangers are awesome. We can single pull in a lot of places where other classes can't, or where it would take them a while to split. We can tank or offtank, even in raids, depending on your gear. We're ok melee dps due to triple attack, but not -great- in comparison due to a lack of any melee specials aside from kicking. We're awesome ranged dps; I've hit for 9900 with my bow, and I regularly crit for 6k on raid bosses. Once you get all the ranged dps aa's under your belt, you can get faster aa/tome xp solo than in most groups, if you know where to go and you don't already have a massive zone penalty there
As far as ranger flaws go, fletching is my #1 complaint. If you want to be your best on the field, you have to get your fletching up. Fletching is expensive and really not a viable option for a new player until you're in your 40's or 50's unless you spend a lot of time just farming up lowbie coin. Combines also get really expensive as you level up your skill, and the cost doesn't really even out with the quality of the arrow in my opinion.
Another downside to rangers is the spell set. Sun Quiver is something that isn't good to use outside of soloing; if there were places to do high-end kite groups, Sun Quiver would kick ass. Unfortunately, all it really does in groups/raids is pull aggro to you when you really don't want it, with no real beneficial increase in damage. Spreading Snares is only good when you're tanking for a group and you need AOE aggro. Don't try to use that to kite multiples unless you like getting smacked around! Last of all is Firefist. Firefist rocks, but an upgrade to that would probably make the day of every ranger on the server (hint hint!).
If you have any more questions, let me know.