Well, for me low libido and feeling depressed is enough reason to want to stay in the normal range, with low-normal absolutely fine for that, and you’re right regarding blood lipids as well (though if using Clomid during a cycle it may be the case that it can substitute for estrogen for this purpose, however these days I don’t do that) but also just out of general philosophy I don’t prefer driving something which in fact has good use in the body, when at proper levels, to abnormally low levels when there is no upside to doing so and it can be prevented.
Also many who have experimented with AI’s and overdid it have really not liked it, as well as most of those using, against all advice, trenbolone-only or other non-aromatizing completely-suppressive cycles for more than just briefly, so it seems a general finding that driving estrogen too low isn’t good.
On the liver protection, while it’s a good-enough sounding idea I’m not aware of any evidence (that doesn’t prove it doesn’t exist, it just means I’m not aware of it) that there’s anything that does anything for the effect of 17-alkylateds.
There’s at least one study showing milk thistle to do nothing in some animal for this purpose. Not that milk thistle is a bad thing: it’s a good supplement. But whether it makes a difference in this application, I don’t know. Certainly against the most severe potential problem, hepatic cholestasis, it can do nothing.
Doing 2 on / 2 off you should have no liver issues.
The biggest issue with 17-alkylateds, by far IMO, is duration of use. Not daily dosage – a lot can be tolerated there – but duration. In other words I would rather see someone take say 300 mg of alkylateds a day 2 on / 2 off or in traditional cycles with the alkylated use not exceeding 6 weeks at a time, than see someone take 5 mg a day indefinitely. This is based on there being cases of women suffering serious liver problems from as little ongoing use as that.
The liver regenerates quickly, when the insult is removed. Your giving it the off time that you are is all that is needed, I believe, to stay safe with it.