I think the primary reason LCGs don't have higher market share when compared to Magic and others. Is that LCGs lack High fidelity and high convenience. Fidelity means the aura and the emotional impact that something projects. Objects with high fideltiy are difficult to obtain and/or expensive For example, U2 concerts have high fidelity because they are expensive and hard to get tickets. It isn't convenient to go one. You can only listen to a few artist there. Yet U2 sells out all the time. On the other end of the spectrum, you have the the Ipod. It is ultraconvenient to have thousands of songs at your fingertips, and it not expensive. Ipods also do not project an aura (no fidelity) because they are also so common. Products usually can gain fidelity at the expense of convenience or vice versa. Look at Starbucks. Thier product started with large amount of Fidelity, and people would pay 4 dollars for coffee. But when they started putting a Starbucks on every corner. The company increased the convenience to have Starbucks coffee, but lost the fidelity of the experience. Thus people felt they where over playing for that same 4 dollar coffee.
Now lets appy this to the gaming world. Magic and other popular ccgs have one thing in common. They have strong/must have cards at High levels of rarity if you want to compete. This increases the fildety of their product. Because if you pull that ultra-rare that one else here there is an emotional impact or an aura that card projects. You have something that others in your play group know is hard to get/expensive. At the other end of the spectrum, you have boardgames. Boardgames offer you the convenience of all components to be competitive in your playgroup in a single box. Boardgames can increase thier convenience by packing expansions with their core and including other formats for the game (different maps, rules, etc) A good example is the Chaos in the Old World. It all the pieces in one box so that you can be competitive with your playgroup.
Breaking down LCGs, you have mid-range fidelity with the cards you only get one of, but you know you can get those cards more easily than pulling ultrarares from magic. You just need to buy more coresets. This brings me to the second point is that LCGs aren't really convenient as a board game because you don't have all the components needed to compete with your play group. But it is more convenient than pulling those rares out a magic box. I feel that FFG is trying to make their LCGs convenient and have high fidelity. But you can't have both if you want your product to do the best it can in this market. I do believe though that FFG did do a better job of increasing the convience of getting into Warhammer:Invasion by offering 3 or 2 copies of certain cards.