The D100 had MLU as well. My D80 has a function that comes pretty close to it (it adds a delay of 0.4 seconds between moving the mirror and exposure) or you could use the self-timer as people have done for ages.
In any case, I doubt this is really, really the missing pro feature.
No, the D100 had a 1s pre-fire, *not* MLU. Under some conditions the mirror going up would still affect the stability of the platform- which is why Nikon's pro bodies have had MLU on them for about as long as I remember.
While it may not be important for your work, I find it very important when I need it. It's important enough for my shooting that I won't go down to one of the consumer bodies as a back-up *because* of the missing MLU.
But then I doubt that you're shooting any of the extreme telephotos if you're not thinking it's all that important. I routinely shoot with a 400/2.8 AFS-II and resort to the TC-14E-II and TC-17E-II teleconverters when I need them, and I use MLU whenever I can. If you're the kind of shooter that rarely shoots from a tripod then it's moot. If you always shoot from a tripod, it's an extremely valuable feature.
Besides, the point is that it took Nikon *decades* to move this pro feature down *one step* on the ladder.
With the exception of the D40(X), you can use any AF lens on all Nikon dslrs (with the exception of IX Nikkors designed for the short-lived APS slr cameras), everything works. Non-AF lenses are different, usually metering doesn't work anymore. Since non-AF lenses are increasingly rare, this is not an issue for most people. Remember that you can't really use FD-mount lenses on Canon EOS bodies.
Look at the lens compatibility of the D200 and D2x, then look at the lens compatibility of the D40, D40x, D50, D70s and D80 and then tell me the compatibility is down in the consumer-level cameras. It isn't. It's not moving down either. "Not an issue for most people" doesn't mean they couldn't put the same firmware (after all, it's already written) into the entire line-up. Since non-CPU lenses are less complex, it's not like this is going to be a huge support cost and since it's "not an issue for most people," it's not like they're going to lose huge lens sales momentum by adding it. I don't care about using FD lenses because I don't shoot Canon.
http://www.nikonians.org/nikon/slr-lens.html
Note that on any of the pro bodies or the D200 (which is the Nikon "exception" camera) you can use manual focus AI, AI-S and E lenses in aperture priority and it'll meter, now look at every consumer digital camera- no dice. Another "Pro" feature not moving down the line all that quickly.
With the exception of the D40(X), Nikon offers vertical grips (as add-ons) for all their dslrs. Only the top-of-the-line pro models of both, Canon and Nikon, have built-in vertical grips.
As add-ons, which isn't the same as moving the feature down the line- and can you provide the part numbers for the D70 and D50 grips?
The D80 uses the same AF module as the D200; the D40's metering system is derived from the Nikon F5, while the D200's is based on the successor. Technology surely trickles down from the top.
Slowly and as a function of reusing parts, not as a function of moving power down unless there's a competing feature. Frankly, I'm not sure that championing Multi-CAM1000 is much of a benefit anyway- for the time I had a D200, it certainly wasn't overly impressive in terms of AF, and the fact that the D200 didn't get Multi-CAM 2000 pretty-much proves my point. The D300 announcement is a good thing (though it's not a consumer-level camera) because it shows that Nikon is going to reuse a lot more features over time (which they've said they'll do for efficiencies sake- no spinning at all AIR.)
Want to give me the wireless transmitter and GPS features for the D80? The D3 puts us on the fourth generation of the WT series, surely by now it'd be moving down the chain if Nikon were so magnanimous in moving features down the chain? Heck, isn't it even in some of their P&S bodies?
I've only been shooting Nikon bodies since about 1991- but in that time, I've not seen a lot of evidence of them pushing to move features down the line in any timeframe that wasn't driven by the competition's feature list or overall market evolution, and even then things like MLU (and frankly even pre-fire) have been offered lower down the tree by the competition more often.