I think that the trap is, by the time you really need to move it becomes very difficult. If you don't really need to move, you don't want to because it's not relevant to your current lifestyle. I know the advice for people is to move to more appropriate housing before they really need it, but that's not taking human nature into account.
I think a lot of people don't realise how very quickly their situation can deteriorate. 3 years ago my Dad was a bit doddery and forgetful, but still very active, strong, funny, full-on, himself. Now he barely speaks and is bed-ridden. But then again it's a gamble, for every older person who ends up like my Dad, there's probably 10 who don't really have very severe problems at all and can live independently until they die. Like my 98 year old relative who lived alone, needed no outside assistance, and was still going to play the piano once a week to help entertain 'for the old folks' at a community centre. So you might move into sheltered housing, and find that actually you never needed to have done.
And there's also the risk of another move after that. If you have serious needs then you may need nursing home care, so your 'retirement home' isn't your final home anyway. If you don't have serious needs, you can probably manage in most properties, with some changes, support and adaptations. So you might as well stay where you are already happy?
My and DPs parents are both mulling these all over at the moment. Some days they think yes let's move, some days they think not. I doubt very much either of them are going to. It's now too late for my parents - sheltered housing etc won't take new residents in my Dad's situation. So all they'd do is move to a smaller more manageable ordinary property closer to family, but then also lose all their local friends and support network. Difficult choice. DPs parents already have a bungalow but were looking to downsize a bit to make things easier for them when older. After doing the sums of estate agent fees, stamp duty, removal costs, etc etc they've decided fuck it, stay where we are, and use that money to pay for gardener/cleaner when we can't do it ourselves.