Bb on a C harp...why?

[Roger A Gonzales <gonz1@xxxxxxxxxxxxx>]

OK, I would like someone to explain the advantages of playing in the key of Bb on a C harp.  W.Va. Bob, this has nothing to do with your question about positions so please don`t take offense but I have to ask this question.
  
Let's see.  if you are playing Bb blues, the I IV V7 are Bb, Eb, and F.  OK, the chords are Bb, D, and F.  OK, you can hit all the notes in the chord on this one.  The IV chord Eb, you have Eb, G and Bb.  You don`t have an Eb and there is only two places to get a Bb and that is on the 3 draw and the 10 blow.  Horray for the G.  The V7 chord which consists of F, A, C, Eb.  Hey great! I can hit all three but where is the Eb if you want to hit the lowered 7th.  
If you want to play Jazz on it the most common chord progression in the ii V I.  The ii chord is a C minor chord which is the Eb which you cannot achieve on a conventionally set up harp and it happens to be the most expressive chord tone you have in the C minor chord.  
I have a hard time believing that it is for more expressive playing or to improve your technique.  Its like trying to paint an entire house with a 2" wide brush.  You can get the job done but man why wouldn't you want to use the right tool for the job instead of one that will take you forever and make your your job a drudgery.  
I love what Paul deLay said when I asked him about playing in different positions.  He said, "hell I'm still trying to figure out everything I can do in second position." 
Unless you have completely exausted 1st, 2nd, and 3rd positions then there is alot more expression and technique to discover in just those positions.  
I still am wondering the advantages of playing in these positions instead of using a harp that will give you more of the notes and chordtones that will make your playing fluid and the intonation correct.  

regards,
Roger Gonzales