The main problem with scoundrel is that most of the skills are not worth using for damage. This leaves you in a position where standard basic attacks in the backstab position are pretty much always the best option. Even most of the utility options are outdone by low level magic spells you could pick up for a few skill points. Even if their raw damage is high, having basic attacks be your best option is just not fun play, at least to me.
At least marksman offers a few decent attacks and a couple decent utility skills that are very much worth having on your bar and using. Then the variety in arrows gives another addition to the combat for them. While they may not have the same raw damage as 10 backstabs in a row, it is more entertaining and fun to play.
Man at Arms really only has a few good damage skills and a few good utility skills as well. The main reason it gets a lot of attention is 2-hand damage output. If it was not so high compared to everything else then people would complain just the same. The only thing people talk about with man-at-arms is the uber damage they do. It doesnt offer anything else.
It seems to me that you're not understanding the point of skills for weapon classes. Damage isn't the point, nor should it be. Man-At-Arms has some great skills for utility, such as Battering Ram, Crushing Fist, even Cure Wounds, which make even pure warriors more than simply dishing out damage to the face. However, when these classes are dishing out damage, it should
be with normal attacks primarily, and much less often with skills.
Razor's Edge and Trip those are good skills. However, Cloak and Dagger is a little unwieldy, with a AP cost of 6 and not even available until level 10, which means Rogues are sorely lacking in mobility talents, especially early on.
Here's what I'd do...
Trip is now a Marksman (starting) skill and does not require any particular weapon to be usable.
Tactical Retreat is now a Scoundrel (starting) skill, renamed "Jump" (perhaps with an adjective, such as "Precise Jump").
Cloak and Dagger is now a Marksman skill, renamed "Tactical Retreat."
Rapture is now a Scoundrel skill, renamed "Conspire."
This would give rogues access to a cheap (4AP) teleport skill, available very early in the game, without having to spend a point in Marksman. It would also give Scoundrels four (not three) starting skills to choose from. And a Marksman with sufficient Charming Arrows doesn't need Rapture anyway.