I hate to sound like a right-winger, but seriously, where was this hue and cry when Clinton and Obama were doing it?
Personally speaking, I was a child when Clinton was president and I don't know much about his use of drones, so I can't really comment. I would bet that this applies to a significant percentage of the people objecting to Trump's actions in Venezuela.
As for Obama, there are several factors that contributed to the (relative) silence from the public:
1. He didn't gloat or brag about it. I think Trump's (and his administration's) attitude on this is a big part of the pushback.
2. While he was definitely pushing the boundaries of the 2001 AUMF, there was at least
some connection, arguably, between the people that he was going after and Al Qaeda/the perpetrators of 9/11 given that they were all Islamic terrorist groups in the Middle East (+/- Africa). Therefore, what he was doing was officially under a blanket Congressional approval. In contrast, while Trump is
asserting that this still falls under the AUMF, there doesn't appear to be even the weakest of connections between South American drug traffickers and 9/11 and he hasn't even tried to claim one. The fact that Congress hasn't objected
technically means that this is still Congressionally-approved, but the blanket is wearing mighty thin.
3. Americans have generally been conditioned to accept that people associated with terror groups are legitimate military targets. Trump is trying to play into that by calling drug traffickers "narcoterrorists," but I don't think most people are buying it.
Personally, I was uncomfortable with Obama's use of drone strikes in the Middle East, but I was also significantly more trusting of the government at that point in my life and generally assumed that he was taking necessary actions to protect the country. The last decade has done a lot to erode that trust, and I specifically don't trust Trump to have the best interests of anyone other than Donald Trump in mind.