Well, yeah. These mods add too much, like, way too much monotonous and outright boring grind to get to the fun part - fighting the liches. In Shadow of Mordor/War, which was the referecne for lich system, fighting bosses is fun because you can try to kill them whenever you want after you get intel on their identity or simply meet them. Of course, if the boss is too hard, immune to your preferred attacks or something, you need to gather more intel on him and take your time to prepare, but that isn't mandatory. No hours upon hours of pain and chores. Returning to the packs, it looks like "create a problem, sell the solution" in the worst sense of it. Not "pay to skip", but "pay to win"
I believe, the lich system meant to be a challenging endgame content which means players need to actually achieve (same with ephemeras) the victory, not buy it. And "challenging" means actually having to fight the boss using the right strategy to defeat it, not layers of RNG, not the grindwall, even a pay-to-win one. The things get worse because you can't skip a useless lich and killing one takes as much time as one with good weapon.
As for finances, I understand that supporting a game like warframe isn't cheap. But pay-to-win shouldn't be a solution as it decreases the overall quality of the game. A subscription woud be better.
DE, we believe in you. The lich system as an idea is great, but it needs balancing and polish to be what it meant to be.