Yes, the reflex sights and scopes are getting better. From 1965 to 1995, I saw the bolt gun makers go from iron sights included on every gun, to sightless guns available for order, to sighted guns available to order, but most on the rack set up for scope mounting. By the time I bought a Rem 700 in '92, iron sight bolt actions were few and far between. Pro hunters recommended taking another scope mounted with matching rings already sighted in for trips overseas.
The military adopted reflex and red dots once the technology was proven, and it's been a big help. As a red dot user since the first generation Aimpoint, todays cheap version run circles around it in everything but quality.
Nonetheless, for combat, glass lenses are not durable enough to rely on, a set of iron sights is the only thing you can trust 99.44%. If they go bad, you really are having problems.
For a hunting, recreational, or range rifle, BUIS are an expensive, weight adding, and unnecessary redundancy to a rifle, especially an AR. Another red dot or reflex can be mounted for the same money as iron sights. What many are overstating is whether that recreational gun even justifies the cost. It's NOT a life and death duty tool.
On a duty gun, I would only use milspec iron sights - because they are the most durable, cheapest, and failure free design. All the clampon BUIS sold cost three times as much as a standard FSB and carry handle M4 rear sight. They are NOT more durable OR more accurate, they are just cooler looking and cost more.
I built my AR with milspec sights because they are, and only cost me about $65. They will not crack a lenses, go dead, eat batteries, or fall off. They also won't be as fast or easy to shoot as a red dot, so for hunting, that will be my primary sight. If the gun falls over in the parking lot and the optic fails, I can take it off in one minute and continue the hunting trip not much the worse. Just like scope users in the '50's and '60's.
In another 25+ years, optics will be even more durable - with Gorilla glass lenses, like touchscreen phones, and nearly unlimited battery life, like an Aimpoint. They may actually be sealed units not serviceable by the owner, meaning one less gasketed joint to fail, making them even more durable. Putting the windage and elevation back in the base will mean no inverter or fancy machining, or intrusions to the sealed interior. The only openings will be for the lenses. Completely maintenance free. Just not quite bullet proof, but neither are iron sights.
And I don't want to be holding that carbine in the live testing phase ....