If this sounds "too painful for the animals" to you, then other things done routinely in medical research would be 100x times beyond "pure torture" or "hellish"

If this sounds "too painful for the animals" to you, then other things done routinely in medical research would be 100x times beyond "pure torture" or "hellish" to you, meaning your cruelty threshold is waaaaay dis-calibrated. Thankfully researchers have learned to "forget describing" the painful effects or use "over-technical description of procedures avoiding the perceived pain by animal subjects", so they can actually not be noticed by people like you, and carry on working on things like curing cancer and other important stuff. Also, the "is it really worth" question is the dumbest thing to do in science - most scientific discoveries are valuable because of their unforseen and unintended consequence, so saving cures can come from a 10th level consequence of "pointless research" (that could have gone unfounded because someone like you might've said "but is it really worth the cost [in animal suffering]?"). Better wake up and see the cruelty that is all around us first, including abundant human-to-human cruelty everywhere, and adjust your cruelty-tolerance threshold accordingly!