boron is an essential nutrient for plants, they are handy to have around. it is also an important part of ceramics and semiconductors.
beryllium is used in semiconductors and the metals of electrical contact surfaces.
Nobody doesn’t like Molten Boron ™!
Yup. Krypton is used for producing the Man of Steel, not defeating him. That still makes it useful though. 
It is used for high powered semiconductors. Manufacturing, wise you need to be especially careful. But once it’s fired like a ceramic and one doesn’t take a hammer to it and snort it up like blow, it’s safe to handle. AFAIK, you can toss it in trash without a permit.
Evidently you’ve never had roaches 
The most stable isotope of Lawrencium has a half-life of about 3.6 hours. I don’t know if that satisfies the OP or not, but there doesn’t seem to be much use for it if it could be generated in larger quantities.
Boron is also useful in the nuclear industry, where boron can be a useful poison: an element that will capture neutrons without emitting other neutrons - stopping or damping neutron chain reactions.
Boron is also used in the Suzuki reaction and the Chan-Lam reaction. The reactive species is actually a boronic acid or a boronic ester.
How did this become a boron appreciation thread?
And borohydrides are great for mild reductions. I always felt weird reducing esters and mixed anhydrides to alcohols in THF/water, since NaBH4 reacts with water, but that solvent combo always worked best for me.
Just about everyone who wears contact lenses uses boric acid, as a part of their saline solution.
Nobelium is useless. Interesting, but useless. It has a half-life of 58 minutes, according to Wikipedia, so there’s not much you can do with it.
Boron is awesome, if only for its unique role in the synthesis of many organic compounds and strengthening of plant cell walls.
Off topic for this thread, but browsing through the periodic table on Wikipedia, copernicum was news to me.
On topic, I’m not sure the world would be too distraught if ytterbium vanished overnight.
Handwavium?
beryllium is also used in model boat propellers, alloyed with copper.
Beryllium is also alloyed with various transuranic elements to create neutron emitter sources. (PuBe sources are just too silly a name to forget.)
Thallium is toxic too.
Doesn’t seem to garner much public notice either . . .
I think it was once used as a rat poison; too lazy to cite it, though.
As long as we are fawning over Boron, don’t forget it’s application as a p dopant in semi-conductors. Boron amine complexes are being looked at for hydrogen storage. Boron Nitride nanotubes are all semi-conducting.
What about scandium? I don’t know of any uses for that. Also, while the Noble gases may have uses, many of the uses are interchangable. We could probably do without argon. We would just have to use one of the other noble gases.
Nah, argon is just too useful in synthetic chemistry. Most of the time nitrogen is fine for an inert atmosphere, but there are times you need argon. I can’t think of any example of the use of a different noble gas for that purpose.
I vote for Unobtainium. It’s not so much that it’s useless. Just impossible to get ahold of. 