If the "right" doesnt view Russia as an enemy and with great caution they should be renamed the "wrong".
The remark was outrageous because it shows a complete lack of diplomacy and intelligence on behalf of Trump. Its the kind of stupid off-hand remark that can cause international incidents. If Putin gave a speech in Moscow and off-hand joked about blowing up a US ship, it would not play very well here. It would be seen as a provocation and contribute to the idea that Putin isnt thoughtful or, worse, is an impulsive madman.
Some of Trump's method to speaking is refreshing in that he doesnt seem to give much thought to the words that come out of his mouth so you never really have to guess at what he's thinking, what he really means or what the mindset of government is. I might admire those qualities in, oh I dont know, maybe my boss...maybe my lawyer. Maybe my mechanic. But leader of the free world? I think erring on the side of careful is better then careless.