The Wii U also needed to be backwards-compatible with the Wii, which used the bespoke paired singles and locked cache line features of the GameCube's PPC 750 derivative. This almost certainly locked them out of newer PowerPC designs without more engineering work than Nintendo would be willing to put into its systems.

For context, Nintendo has always been weirdly quirky and low-buck when it comes to core silicon engineering. The Switch is a Tegra X1 in a trenchcoat, the SNES used a 65C816 at about half the clockspeed it needed to be[0] and had half the VRAM removed at the last minute, and the NES stole[1] the 6502 masks so they didn't have to pay MOS for legit chips. All of those design decisions were made purely to improve margins and genuinely constrained game developers in the process. "Lateral thinking with withered technology" is kind of just their thing.

At least now they're 100% on board with a silicon vendor with a sane roadmap, so they'll at least have a steady supply of backwards-compatible last-gen chips to repackage.

[0] At least it wasn't as slow as the Apple IIgs they pulled it from

[1] Technically legal as IC maskwork rights did not exist yet. This is also why decimal mode was removed - it was literally the only thing MOS had a patent on in the 6502 design.