I don't understand the point about battle damage assessment.
You have to know you've killed a reentry vehicle or missile bus to know to stop engaging it, obviously? The benefit of nuclear mines and kinetic kill vehicles is that they provide instantaneous feedback to whether or not a bus has been eliminated: it's in multiple pieces and partially disintegrated. A laser doesn't offer that outside of atmospheric interception. Even the SDIO knew this, which is why they didn't consider the laser useful for space-based intercept. The idea was to shoot down the ICBMs as they left their silos. It's incredibly silly but it was an incredibly silly time.
Making a space based interceptor that can attack the booster stack before it's separated the bus is both technically easier and likely cheaper to launch on the aggregate these days. Lasers as ABM systems should have died in the 1980's but launch costs made space-based interceptor/Brilliant Pebbles scary...back then.
Now it's not because a private company can fund launching tens of thousands of 50-150 kg satellites into orbit from internal revenue alone. It would be trivial for the US government to do the same because it has an actually functional, Soviet-style rocket factory these days.
KKVs are limited to exo-atmospheric intercepts and single use.
Making a trans-atmospheric space-based interceptor is easier than making a FEL capable of taking down an ICBM in all honesty. We already have them, after all, in the form of reentry vehicles: they transit into space and come back down. There's no reason one can't sit in a life jacket, with a propellant bus and solar panel stapled onto a backpack, and some sort of high power communications to a SBIRS-LO or space radar system.
At no point do lasers enter the equation. They are antiquated and made sense when 24-48 supersized chemical lasers, which can actually destroy an ICBM, would not be much more expensive than lofting 3,600-36,000 Brilliant Pebbles.
Spacecraft launch costs have tanked because SpaceX discovered the lost art of Soviet rocket factories, but the costs of large satellites still exists, so there's no hope for big SDI sats when a glorified cubesat swarm is easier in every way.
I don't see why you would need 50 KKVs per interceptor for MOKVs
Because there are 50 targets and you don't know which ones are warheads and which ones are decoys? That's the point. Decoys are genuinely hard to discriminate until they hit the upper atmosphere during their last minute or so of intercept and this hasn't changed.
Fort Greely has about 40 GBIs primarily to engage literally "a couple" ICBMs from North Korea at long range, which can be assumed to not use something silly like antisimulation decoys, but rather something like a chaff corridor that can be discriminated against by an S-band or X-band radar, and given the large number of bands involved the North Koreans may not have sufficient chaff to produce a thick corridor. Mylar balloons would likely be involved, which can be determined from ballistic coefficient over the course of about three to five minutes through the exosphere, using LRDR. I don't think anyone expects high powered radar jammers or more modern systems, as that's probably beyond North Korea's capability. Maybe.
Even if it is, SBIRS-LO can discriminate as well, which was part of its original job, and the Space Force may get more advanced systems in the coming decade or so than SBIRS-LO to do the job, as they seem to want to replace the highly expensive GEO systems with a much cheaper and more accurate LEO system. NGI might be able to expand that to five or six if they had the same number of them with multiple kill vehicles per.
Conversely, the A-235 Complex can stop about 8-12 ICBMs of MX/Peacekeeper type with its entire arsenal of 84 interceptors, but the Moscow Missile Defense Complex been partially disarmed IIRC with the retirement of the 51T6 and maybe partial disarmament of the 51T6. It might be able to stop about half as many warheads with just the short-range interceptors tbh, but a terminal intercept is the most reliable against sophisticated decoys anyway, and 51T6 might as well be a supersized Sprint.
America is simply making an assumption that North Korea's penaids will resemble the UK Chevaline's chaff clouds, and simple mylar simulation balloons, rather than more sophisticated Russian or US-type antisimulation penaids. This may or may not be correct (though it probably is) but it's what LRDR is built for, rather than A-235's assumption of highly capable MX-type penaids.
If America wanted a modern ABM system, one built to stop the most effective forms of ICBM attack, it would be better served building launch silos in suburbs and radars near its major cities, with eventual expansion to space-based interceptors for boost-phase interception.
