If you haven't read it, there's a DS9 novella set after the series that took a good look at Trill society, especially the Joined vs. Unjoined tension. It covers a lot of ground and I rather enjoyed it. IIRC one major plot point is that it gets leaked to the public that many more Trill could be joined if they wanted to be than was generally believed.
I see where you're coming from in terms of "erasing" who they are, but I imagine many people would view it as "enhancing" who they are. As an example, I used to do medieval reenactment, and the idea of having the memories and experiences of someone who'd been there for the actual events is intriguing.
I see what you are getting at, and it's one thing to want memories of a previous era through someone else's eyes. Joined Trill, based on what we've seen in the franchise, is more than just having memories of past lives and eras. It's a blending of all previous hosts and the current host.
Best way I can illustrate my point: a STARGATE SG-1 episode called "LIFEBOAT" had Daniel Jackson's head mixed with 10 or so other people. One of them was an engineer from the ship SG-1 discovered. He showed Dr. Frasier a glass of water. As soon as you add more water, that original formation of molecules is forever changed because it's impossible to take out precisely what you added. Same principle with the joined Trill.
I don't think it's a coincidence that shortly after the events of "INVASIVE PROCEDURES", we start seeing Dax do a wide variety of things that we never expected, such as being more open (you can see how much more of a relaxed conversationalist she is while talking to Pel in "RULES OF ACQUISITION") and wrestling an alien in the morning ("PLAYING GOD"). Having been briefly joined with Verad may have had no lasting impact or effect on him, but the Dax symbiote remembers, and Jadzia said as much at the end. Because of this, we basically saw two versions of Jadzia Dax in the series... the original was more cerebral and withdrawn, while post Verad was outgoing, active, and much more playful sexually.
In that way, it's a sort of death of personality. While it definitely can be argued it's an enhancement, like how we see Jadzia act before and after Verad, it still comes dangerously close to wiping away a personality.
(In a sense, joined Trill represent a sort of slow version of a regular human lifetime. Each 'host' is like an era or decade for a person... we are different people as children, as teenagers, and as adults in our 20s, 30s, 40s, etc. I am certainly a different person as a married man in my 40s than a bachelor in my 20s... most of my values and personality are the same, but I have a different set of priorities, my views on certain subjects have changed, etc. In that way, we also have a sort of death of personality simply because of experiencing life over decades.)
I guess I went too far off this tangent, but I hope I've made sense.