I have no problem if someone downvotes a post for valid reasons but doing it just because they now get rewards for it made no sense to me.

They don't get rewards for downvoting, it goes back into the pool.

I have like I said only ever moaned once about this and now I tend to simply ignore and carry on. Most times the accounts downvoting are brand new accounts with low reputation and little to no SP.

Move on regardless I think. In the last 2 days about 20 downvotes removed a fair bit of potential Steem from my posts and those who curated them. Roll with it, don't get emotional :)