Again, we can try doing that with Marksman as an example, as ranged attacks are one of the most common rolls in the game. So let's say a Character has Marksman 3. That means he hits on a roll of 7 or more. So would his "BS" be 7? More importantly, did we actually make anything easier by saying so? There are 27 (!) modifiers in addition to a Character's level of Marksman that could affect the "to hit" TN of a given shot, and no way for a static profile entry to reflect them.
Rather than thinking about this in terms of profiles, which is kind of a square-peg-meets-round-hole situation, it may help to remember that most of the time the TN is 10. So all other things being equal, a Character generally has a 50-50 chance at succeeding. From there, the chance goes up or down (usually in 5-10% increments) depending mostly on the circumstances.