For me it's the Maul battle (R7) that makes me want to throw my phone through the window. I got the hang of the strategy, and my mods are decent (not god-tier, but not pathetic either), but with all that healing back to full health and protection, the enemies constantly outspeeding me (especially when a wave with STAP in it starts) and getting bonus turns because of the modifier is really taking its toll on my sanity.
Otherwise, yeah, I agree with what you said. There is so much RNG in this raid it's not even funny. As the difficulty increases with each tier, so should the bonuses (tier and hero) be decent enough to balance it out while still making it feel like a challenge. But just look at the hero bonuses, for example, they're downright pathetic compared to what we had in the Krayt raid. And take the Lumi team, it relies extremely on having both HoT and Potency Up to work, yet the moment the enemy gets the bonus turn modifier, you either end up with one of your toons (in most of my battles, QGJ) dead or you have a hard time keeping those buffs on because of how often the Command droid goes and uses his special (which FYI is bugged in terms of cooldowns, it's supposed to have a 3-turn cooldown, yet each time the droid uses that special it instantly starts at 2).
The Krayt raid was very good, it had new yet easy to understand mechanics, the difficulty was reasonable on any tier because of the bonuses. The only downside was that it ran too often at the time, and thankfully CG actually listened and decided to fix that. But ever since then, the raids have been nothing but ridiculous. The execution I mean. The ideas and themes at least were interesting.