To not alienate 20 milllion users
Plus
http://www.neogaf.com/forum/showpost.php?p=39316116&postcount=259]
Actually, the reasoning really seems quite simple, unless I'm missing something, and if I'm not, it's strange more people haven't realized the actual problem just throwing a second stick into the system would cause.
The reasoning would seem to go back to the original Circle Pad Pro which, since it wasn't built in, it needed some other method to communicate with the 3DS. This method was Infrared and if my understanding is right it's how games know when the CPP is connected. And that's where the problem comes in: Just building a second stick directly into the system wouldn't work since without it using Infrared, the current CPP games would have no idea what to do with it and would just ignore it (a potential solution to this would be to have the built in second stick communicate using IR anyway, but that would mean the inability to use the IR sensor to communicate with anything else due to interference from the second stick, so that's really no good). Or in other words: A second stick built into the system would not be able to have backwards compatibility with the current CPP-supported games.
That's naturally quite an issue and would lead to a great deal of confusion among people if they tried to use a dual-sticked XL in such games, like RE: Revelations and it didn't work. But of course, the problems wouldn't only be with the current games, but would extend into the future as well: If the XL had two sticks built in, since it wouldn't be using IR, that would mean developers would need to add support for the CPP and the second stick on the XL separately, as they'd each be using different methods to communicate with the system. And even the developers who'd want to support a second stick probably wouldn't want to bother with something like that.
Pretty much, despite it hardly being an elegant solution, keeping the Circle Pad Pro was pretty much the best and only way of addressing such problems. The door was pretty much shut on any other ones the day the original 3DS shipped without a second Circle Pad. Any other solutions would just either lead to fragmentation of the userbase, breaking support for previous games, or both, so really, thinking about it, continuing the Circle Pad Pro for both versions of the 3DS really seems to be the only real solution to me.










