[Dynasty]

The problem with medium and small straight draws such as 8c7h6s or 5d4c3h is that they only have one practical way to win a hand- by making the straight. It is unlikely that either of those two hands will win by making another hand such as two-pair.

Compare that to flush draws such as Kh7h4h or Qc8c2c. Those hands can win by making their flushes. But, they can also win by making a two-pair hand such as Kings-up or Queens-up. Flush draws with big cards in them have the added pair making value to them which medium and small straight draws don't have.