Don't forget they had an N64-era game on the DS since launch.
I actually think the PS1-era Legends controls are pretty awesome. You have full manual control of both the character and camera at all times without the need to move your thumb off of jumping/firing buttons. Very convenient once you get used to it; I actually modify Armored Core controls to strafe with the D-Pad so that it mimicks Legends. It's definitely the most comfortable way to use digital inputs to control a 3D character (I hate DualShock stick locations).
There's also the fact that Trigger invented the invulnerable dodge-roll. And does it a hell of a lot better than Axl. As far as maneuverability goes, that's a big one in his favor.
Of course, making a more "modern/general" camera system for movement akin to Mario might be in the best interest of series survival. As much as I love the controls I know the rest of the world doesn't feel that way. Maybe they could do both and let you switch in the options. I know they tried to be accommodating for both styles in Misadventures and L2. There is the issue, however, of if the controls are modified so that you no longer will be turning while standing still, how tumble-dodges will be handled, since that's part of how you activate them.
Heck, I think they should do it on the DS.
I'd still rather see Wii, but this isn't a bad idea. One thing, though: If the game is not touch-controlled, the action should be on the top screen, and bottom screen should be your map/status, not the other way around. It's awkward, for me at least, to be ignoring the top half of the system when that's where the sound is coming from. Most devs seem to agree, looking at various Mario and MegaMan titles that are already out there. This is especially important if you're going to shoot for SM64DS-esque "analogue" movement as an option (although it's not one that I'm fond of), since:
A. Whatever you're using to operate the touch-screen will obstruct your view, and:
B. Since the touch-screen is not circular and has no tactile feel as to where the "middle" is, a visual display of where the neutral location is (SM64DS does this) is pretty much necessary.
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