The only reason is, Hillary's name it's much easier to play with.
Trump has his own extensive business interests and hasn't been in the game of politics for a s long as the Clintons, so he has a less developed or less well known list of big donors who will be expecting special treatment if he is successful.
Calling Clinton $hillary is (IMO at least) fair comment but it certainly doesn't exclude the possibility that Trump will take big donations in return for granting favours and special privileges.
Back when Bush the dumber was first elected (or got in - whether he was actually elected or not), I think there was a general expectation that he would concentrate on domestic united state policies. How incredibly wrong that was, he soon had two wars going, half way around the world.
Even going right back to Thomas Jefferson, who had written extensively about avoiding foreign wars... he was quick enough to advocate for the Barbary war / attacks as soon as he was actually in a position to do so.
So again, we know that Clinton is a war monger (Syria and Libya point to that) - but there's a good enough chance that Trump will turn out to be one as well, regardless of what he might have said about pulling out of Afghanistan or Iraq, with suitable prompting and tweaking of his ego, he'll act like the narc that he is.
In terms of "Killary", your Nobel memorial peace prize winner appears to be rather proud of the power to have extrajudicial kill lists and assassinate united state citizens (including a 15 year old boy on holiday with his family in the Yemen).
now that there is a precedent set, it's going to be extremely difficult to rein that abuse of power back in, even the Bern has defended it.
"Hitlery" - neither candidate is very far from Benito Mussolini, and in truth neither were FDR and Churchill very far from Mussolini either (or Mussolini very far from Woodrow Wilson).
