Is hdmi a must have for home theater?

Frankly I'm shocked at how non-descript this very topic has remained to the general public. I don't hear reviewers emphisizing this point either. As it's very understood that there are a couple of ways to get the HD codecs to play (either internally from a source, connected via analog, or from an HDMI connection to a pre/pro that has this decoding), it's not been made common knowledge as to what the benefits and downsides are to either method.
Can't someone simply set up an A/B scenario to compare? Then give their impressions? I see/hear non of this.
Why is that?
Once and for all, could someone PLEASE put to rest what is doing what on both (i.e, extensive assessment of sound quality differences and attributes) setup methods! Lol. Er at least point us to some pro reviews and such were this is spelled out in detail.
Thanks

"The decoders for the major formats (either traditional DD or DTS or the new lossless formats) "SHOULD" be the same whether they are in the receiver or in the player. As long as the player has all the decoders, simply from the decoding perspective, it really should not matter where the decoding happens." - Dtc

Well let me just add that has simply not been the case over the years - at least in regards to old Dolby Dig and DTS processing in the past. Back when, when codecs could be processed either internally or via outboard processors, pertaining to standard lower rez digital Dolby and DTS, my experience was that it always sounded better using the DAC's in the outboard processor over those in a standard DVD player! Infact, not only did AV reviewers frequently make mention of this fact (if hinting that there were usually lesser processors utilized in the players - if for other reasons) in magazine articles and reviews, but I never found one instance where any dvd player I ever owned, where that was not the case, either!
So, while I've not experimented with the latest codecs, and differing hookup options - pertaining to the latest Dolby Plus and DTS Master codecs - I'm not certain that things are so simple as to say that it should be equal sound and results, regardless of which hook up method you chose! As I said, my past experience, personally, has shown that there are, at the very least, factors to consider. And all things are not necessarily equal when it comes to processing, hook up, preamplification, etc. I guess what I'm saying is, is that I don't think it's just that straight foreward as is being implied here. I'd like to know from some review professionals, at the very least.
Anyone point me to a reveiw article or two? Perhaps have done some AB'ing of their own?