Should we unify and have one rank structure? Why or Why not?

No.

Because tradition, customs and courtesies. Also history.

And just because.

No, the branches are all separate entities with histories and lineage.

No. Even though I could probably think of several different reasons, two of my more passionate reasons are history and tradition. Some may disagree, but IMO each branch has strong foundation of tradition that should not be dismissed by the good idea fairy. It is what helps to define us as branches of the U.S. Armed Forces. Each individual worked hard to attain their place in their branch and have a certain sense of pride which they all deserve to have. I think it would hurt morale to a certain extent by trying to "simplify" things. There has been talk for some time of everyone going to one uniform which I hope never passes, but to totally strip tradition would be a major black eye to Esprit de Corps.

Ranks are fine the way they currently are. I will say however that there needs to be an emphasis on teaching people the ranks of other branches. I personally went through tech school with other branches so I learned them quick but I know many people who won't have a clue what I am talking about when I use ranks from a branch such as the Navy or Coast Guard.

One word. Tradition.

The Navy's Ranking not only goes back in history but also displays a persons actual rating for enlisted and what Corps the Officer is. You can look at a Petty Officer's Rating Badge and service devices to determine if they are Aviation, Surface, Submarine, or Medical and what their Job is. Also the Fowled Anchor of the Chief Petty Officer has Naval symbolism. The Entire Naval Uniform and Rank structure has a long respected history.

I do not feel that it matters that ranks look different in other Branches, that is what makes each Branch unique and it just laziness on the individual to not learn the different ranks of who they will work with.

It would make it easier for all uniformed persons. Then even people fresh out of basic would know how and when to deliver the appropriate respects when around members of other forces.

Unifying the rank structure is not going to solve any longstanding problem but it will squander tradition for the sake of simplicity .....

I see a lot of tradition in our rank structure. Tradition should never be given up lightly. If we are going to change, then we have to go to the Navy Ranking system. The officer sleeve insignia are pretty much standard world-wide. We could not abandon those rank insignias.