So lets say you need to remove threat, you play excavate and hope you hit dmg, if you do you take over tempo if not you “wasted” your mana. How many cards give you random card (from any class) so there is no control in that, literaly anything can happen.
The trick is to know all the possible scenarios from playing each of the cards you mentioned, to assign them expected value and to pick the option with highest expected value. Purely economical.
If you’re not ready to invest the mental energy you need to do that, then I guess, yeah, roll the dice and see what happens xD
But it’s really a one-time mental investment. Once you learn each of the scenarios, you know the values and decisions to make by heart. It’s the same as in Poker, once you learn the ranges and probabilities. In fact, the more rng you have in a game, the more that games approaches Poker in its’ playability, and Poker is all about knowing a possible range your opponent has, and your probability against that range for every board outcome.
That’s what it takes now to win HS.
Or just play an aggro deck without RNG, I guess xD
I’m fine with both. I really, really enjoyed playing Rainbow mage 2.0 until it became tier 3 deck. It’s the only deck I’ve ever had 13 wins in a row in Legend. Plenty consistent for so many card discovery and rng 
Now I just rock treant druid and buff pally, who literally have 1 rng card to worry about (5 mana card draw for druid and boogie card for pally, the rest aren’t that impactful)