Agreed with DX that Black Market is an amazing card for skilled players. I smile every time I see it in the kingdom.
Many things about Dominion are random, beginning the first shuffling of 3 estates and 7 treasures into your starting deck. So when you evaluate a card with instructions and play that add additional randomness (which practically all cards do to varying degrees), you should also evaluate how many interesting and skillful decisions it adds to the game. Black Market pretty much does that in spades and better than any other single card. It's amazing to play with.
It is not even clear if adding "receive a Boon" to a card would reduce our ability to predict the winner (based on player skill) for games using it, vs. if it didn't have that text (and ignoring how much the card favored the better player to begin with). It should make the card more random, but ability to evaluate cards is significant. Maybe the good players have a better grip on how much of a benefit "receive a Boon" is, on when to do the optional things, on how the board is affected.
This is completely on point; I've certainly gotten a lot better at evaluating boons in just the past few days, and this isn't surprising to me.
The real question has always been: are boons fun to evaluate and keep track of? Overall I don't think so, partly due to the online interface not being so great. So far my verdict is "Meh. I can do without these."
But perception is everything. If people don't like Black Market because they think it means the impact of skill is reduced, then they don't like Black Market, and them being wrong there doesn't matter. If you think Militia is fine but Skulk is too random, well, I don't know if Skulk would be above or below Militia on that chart, I don't have the data and it isn't obvious to me, but it doesn't matter in terms of you liking the cards. If you hate Skulk that's that, you hate it.
Hexes are another matter, I very much dislike them. They are swingy in the way that Swindler is swingy -- maybe even more so -- but what makes them worse is they are much harder to counter than Swindler.
When Swindler is on the board without Fairgrounds and Farmland, it's easy to counter. You evaluate how many Swindlers you want based on your action/draw economy (opening double Swindler is often a good play), and you buy a lot of high-cost and especially $6 and $8 cost cards as soon as possible, instead of investing in too many things that will become Duchies. You also want to turn your opponent's Silvers into extra Swindlers if they have enough terminals that you'll make them collide...a surprising number of otherwise decent players miss this and give their opponents a new Silver.
But hexes? Hexes are a nasty roulette. There's varying ways to counter each one, but how do you know which ones are going to hit you? You'd like to be prepared for a plethora of low-probability events, but doing so is expensive and slows you down. The simplest strategy seems to be to try to Hex your opponent a little bit more than they hex you, similar to "winning the curse split". Except it's all a much more random crapshoot.