How important is POA for Health and Welfare?

Ditto what @SoupDragon says.
If you need it and have left it too late it will be a massive ball ache.

I have both for my FIL and it just makes all interactions with health and financial professionals easier.

He was very accepting to getting in place which of course helps.

It definitely means more involvement. Tbh I wouldn't push for it. Try not to worry- nobody could possibly blame you for not pushing her to have one, most people don't.

If you want to, encourage her to write her views down. My experience is that this generation expect their views to be understood by telepathy tbh, or even better by nobody ever discussing it. As a result I have everything written down and signed/witnessed/dated in my GP record and am still pessimistic about it being implemented.

When my mum was in hospital last year i was asked if we had POA for health and they were pleased that we did. I suppose it makes things easier.

I don't think it is something you would ever regret having but you might regret not having it.

I had financial POA for my Mum but not health. It didn't seem to matter, I was never asked for it and when doctors realised her capacity was poor (dementia) they would speak with me.

I wonder whether being her niece would mean having POA is more important than if you were her daughter

I don’t know what it would be like if I didn’t have POA but my father’s nursing home takes seriously both the POA and the Letter of Wishes he attached to it.

It's not as important as the financial POA. If you have good open communication with the consultants you can guide them within reason without a Health POA. Important to have a Do Not Resuscitate statement to hand if that is their wish.

POA for health and welfare is hugely important where an individual lacks capacity to make decisions on these issues for themselves - and that will be most people towards the end of their lives.
If the family do not have this the Local Authority will step in and assume it. I know of one case where they sent an elderly person to a truly dire care home. Family believed that this was not in the best interests of the individual and that the LA had chosen that home as their relative was a self funder and they wanted more self funders in there to subsidise the LA inmates. Very difficult to fight their decision without spending a lot of money on legal representation.

I personally feel it doesn't make that much difference, but perhaps I just deliberately feel that so I don't feel so upset that my mum wouldn't grant one! She has no mental capacity now and is at the mercy of the consultants. She went into a hospital recently and they barely talked to us and made decisions we disagreed with.

It has to be said that LPA doesn't make such a difference as it should, and neither does a living will. LPA should legally mean that they talk to you about medical decisions as if you were the person involved. I've seen that principle ignored and people being treated with things they had specifically refused in writing in advance. It's also quite a burden, or should be.

My view would be that if your aunt has strong views about refusing treatment or types of treatment, LPA is important. If she has few strong views about this and generally trusts doctors, it may not be worth the hassle.