"Casual" has been a buzz word in the game industry lately. Consoles have opened their arms to both independent and corporations to put casual games onto their hardware and distribute them online through their stores. Game portals are a huge success because of the attraction casual games (puzzle games and webgames for example) are to the mass market.
Independent studios have dominated this sector for some time, and the big companies have caught on and are designing game plans to make the most of it. This is good news, many people who play casual games don't play the more core games too often, or at all. So if there was a merge between the two then these players might be enticed to see what other games are out there.
Last I read, in 2007 the female gender filled in 45% of the online game market in America, 60% of the casual market. And these games aren't about horse riding and collecting dolls. The reason I added that last part is because they're the first thing that springs to peoples' minds when they here "a game for girls".
The reason this push is a good thing, is because it will bring more consumers into the market, for all games. Computer gaming is no longer considered a 'geeks hobby', and as the industry matures so does the player base.
A few things Casual games have going for them are: they are usually small in file size, so easy to download; they are either free or very affordable; they can be played in short stints (in a lunch break or 5 minute intervals); and most of the PC based games can be played on a computer of low specs.
Will 'Lylian' be a casual game? naa... but we are borrowing a few things from the casual types to cover as large a player base we can.