The unfortunate side-effect of great serialized shows are that you really can't truly enjoy the show unless you've seen the whole story (read: every previous episode) up to that point.
Really, aside from a small handful of people, it's very hard to attract new viewers to such type of show. With a show like "LOST", someone who just jumps in at any random spot is not able to appreciate the mysteries and the character development of the show, simply because they're not "in the know" about what the show assumes you already know. The mysteries are already confusing enough (which is not a bad thing. It's part of the fun of the show, actually), but without experiencing the trail of clues that have happened in previous episodes, the average new viewer will be even MORE confused and be turned off of a show that they very well might've loved, had they watched everything previously (a very bad thing).
So producers of the show have a very tough decision to make. Do they simplify the show, and spoonfeed what's going on to the viewers as to not turn any newbies away? Well doing so would be very dangerous and could be seen as a sell-out and a slap in the face to those loyal viewers who have been there every step of the way (See: "Alias")
Or do they continue on with the path and format the show has always taken, and hope that newer viewers would either be interested enough to find out about what happened previously in another way? This is the best way, IMO, as it doesn't insult the already installed viewership, and doesn't sacrifice a great part of what made the show so fantastic in the first place. The problem with this is that it relys on new viewers doing their own homework to fill in the missing gaps. Read up on the show on the internet, in magazines, or best yet....buy and watch the DVDs. This is why it's no suprise to see some of the best serialized shows out there being in just about every media format you can find. The producers can't MAKE you recap yourself on what's happened already, but they can give you no excuse to not be able to find a way. (See: "LOST")
So yeah, it's a tough side-effect of having a great serialized drama. You pretty much start out with the audience you begin the show's lifespan on and slowly dwindle down as time goes by and as the show's history gets deeper and more complex. Either we eventually get the cliched "reset" button partway though the series to give new viewers a good hopping-on point and simplifing the show, or we do our best to get the word out to our friends and relatives about how great our favorite shows are, and pass around those DVDs we have to help get them caught up!
I know, I myself have gotten at least 8 or 9 people hooked on "LOST".