If the industry had wanted a CAT IV 1000V multimeter, don't you think that the big players, like Fluke, Agilent, Gossen, Hioki, Chauvin Arnoux and others would have tested their meters to that safety level a long time ago? There is just no requirement to do so.
Amprobe and Brymen at least see a need for it. Just because someone does not make things a certain way does not mean there is no request or demand for it. If Hioki sees a demand for shuttered jacks, why doesn't Fluke? The opposite is true too also. Just because someone builds something a certain way doesn't mean there is actual demand for that form. Sometimes manufacturers force things to be a certain way for reasons like profit or to make it easier for warranty.
Brymen could test their meter to 10,000V, it wouldn't make it any safer than all other UL listed meters, rated for CAT III 1000V CAT IV 600V, in that environment. In all cases, the internal damage is contained, without injury to the user. All we could argue is the size of the bang inside.
So you say that a meter rated at CATIV/1000V does matter when compared to CATIII/1000V when viewed only from the rating of a CATIII/1000V? Well
of course not! It matters when you need a meter that meets the spec, not for some lower spec. So Amprobe, under the same umbrella company as Fluke, are making a multimeter that there is no call nor use for?
So there is no call for meters with these ratings, but at least two big companies make them for no reason? I am sorry, but you have lost me with that one. Again, why doesn't Fluke make meters with shutters on the input jacks? With the logic presented, then Hioki is doing something pointless too. If Fluke doesn't see the need, then it is pointless?
Again..... Buy the meter that best meets the needs of the situation or use and don't buy the ones that don't. If you are working on something that needs CATIV/1000V ratings, then get a meter with that standard. If you want to buy a meter for someone who is always blowing current fuses, then get something that helps prevent that.
The Hioki DT4282 has many things to recommend it over many other meters, including the BM869S. It also lacks some features of other multimeters. If you want those other features and/or a lower price then get the other meter more suited to your needs. It is that simple. Discounting the specs and/or features of a product because you don't care for those specs and/or features does not make them irrelevant for others and their needs.