If you’re going for max stealth (which the NGAD was), you want to absolutely minimize the amount of control surfaces, because those have joints and expose less stealth-optimized parts of the airframe when the surfaces move.

Note that the B-2 and B-21 look largely identical in terms of basic design - this is essentially carcinization in the stealth aircraft domain. It’s the best general layout for minimizing radar returns. Also, combine that with the fact that ACM is actually, finally, beginning to become conceptually obsolete (as a result of extremely capable missiles, unmanned drones that can probably pull 30Gs indefinitely, and directed energy weapons). So these days, in the cutting edge of the air combat domain that the US expects it would actually have to throw down within, maneuverability has stopped mattering quite so much. TL;DR ‘nards on the new stealth fighter is a genuinely pretty dumb idea.

Note that this whole statement is completely predicated on the existence and functioning of an absolute shitload of other support systems and infrastructure, and we’re tearing a lot of that shit up, so who fucking knows what’s gonna happen.

Breaks in continuity of the skin will cause issues. Canards are huge breaks, you go from air to a conductive surface back to air.