While the dot damage is fine- there should realistically never be a time in which our diseases are not already up on the targets we’re attacking, with full uptime. This makes the 2nd part of the bonus not needed like it was in original Cata.
Additionally, since Burning Blood applies on the first hit- your abilities do not benefit until the 2nd swings anyway (since there could be some benefit if it let you skip diseases on low health packs, etc.).
With the Ele shaman tuning, would love to see a little tuning here too that made the tier bonus feel rewarding 