Totaly agree with OP, I always said that XB1 power level be more than enuf for Nintendo.
People don't realise how weak actually Wii U is (0.176 Teraflops, and XB1 having 1.3 Teraflops), and despite that Nintendo Wii U game look beautiful and most of them are running at 720p/60fps.
Infos we have saying that NX have power is somewhere betwin Wii U and XB1, or around 3x stronger than Wii U, so even with less power than XB1 and 3x more power than Wii U, NX could have quite impresive looking Nintendo games runing at 1080p, and PS4/XB1 3rd party ports at 720p.