Just my opinion, but I think the same reason Halloween is "bad" to many Christians (not meee tho!!!! I'm a Christian and I lurve halloween)--because it is a common desire to for holidays to have "meaning" (hence totally ruining New Year's with "making resolutions," might as well pee in the punch bowl while you're at it)
(And yes, most of what we know as "Christmas" was hijacked from older pagan seasonal traditions--So are many concepts, including "communion"--tho to me, the latter is more an example of a deep seated archetype, aka a concept that is so part of the human consciousness, that it can't really be plagiarized, as it does not have a mind, or minds, of origin. The "splicejacking" of the pagan traditions with Christianity, also is sometimes argued to be an inaccurate description, when comparing Jesus, Mary, and, Co. to older deities that SPAWNED said seasonal traditions, such as Ceres and Persephone, tho I think they are too "recent," even tho they are an example, as winter is Ceres mourning her daughter Persephone while she is in the underworld. Similar to Christ being in "the bowels of the earth" after dying on the cross. And if we want to go earlier, winter is Inanna, goddess of fertility, banishing Tammuz the sun and SHEPHERD god to the underworld after he failed to mourn her death in which she hung on a hook for...3 DAYS...before coming back to life. And so on. Goes the debate while I think Christmas is for getting druuuuunk. Either way, it looks like we're celebrating the same deities, just under different names (yes my God is ancient!)
But as far as the "meaning and value of Christmas"--think about it...the only thing ALL the major holidays have in common is an absence of work if you're lucky, and excessive eating and drinking, AKA Indulgence, also if you're lucky. We (at least Americans) are obsessed with what we call "productivity," so if we exceed a certain "fun quota", we must also have a "deep" reason for doing so. We are not allowed to just pig out and get drunk for no reason--we have to be "celebrating" or "commemorating" something. I mean, sheesh, apparently it's not enough that we're setting aside a special day to party in the first place. We have to have a special reason for having fun. I believe that's what it comes down to, but it IS just my opinion, soooo just take it or leave it, I'll live ;) I do think it's sad, though, that things like this are so frowned upon, as I really think with the right amount of PURE self indulgence in their life, people are MUCH friendlier, and loving to their neighbor ;) But enough soapboxing, sorry.
Tho before a fellow Christian takes too much issue with this, I do not need to set aside an annual day to remember who my God is :) If it has a spiritual meaning for you, I will NOT try to take that away, but please don't fault me for my "Christmas meaning" being spiked eggnog and really nothing else. Why spend Christmas judging your fellows, anyway ;)
Thing is, tho, I'm a little confused--what are the theological perspectives you are considering to be "swept aside?" I don't see how Jesus "descending" means that He was NOT also born...? If He was a God appearing in the form of a human, He would be doing both. Christmas tradition is largely based around "archetypal" concepts of death and rebirth, because of the season changes, so it is easy to see how the "splice" took place with Jesus' birth...but a fabled birth here of a god in human form would also be a descent from heaven...is that what you were wondering?
But yeah, in answer, Christmas has no "theological value" to me at all...but I believe value, especially of a spiritual nature, is something that is within the beholder :)