But why uncompress it when you're pushing it as a digital purchase on a system that only comes with 32GB of space?

A desire for high audio fidelity? Even compressed, dual-audio would be large. The first game is also not "EAD Magic Compression" and adding in the dual-audio likely tacked on more GBs over the second game.

Do the second game and the PS3/360 version of the first lack dual audio?

There is no dual-audio on the original Bayo 1 for PS3/X360, it was added this time around when it was ported to the WiiU (I imagine they are using the movie voice actors). Bayo 2 has dual-audio as well.

Ah, that does clear up some of the mystery. Still, the file size didn't double, it nearly tripled. 

What's the problem? I guess people didn't hate digital as much as I had thought. I'm getting the discs. Love how solid they feel.

Considering I buy physical only, this means nothing to me.

Same here! Besides, I don't see any point of buying the digital version if you live in Europe!

My original Wii U will likely be absolutely fine. My NES and original GameBoy are both in perfect working condition, and both are close to 30 years old. Same goes for every other piece of Nintendo hardware I own (and I own basically all of them), so yeah, I have no worries about that. The fact that your games are tied to the system will be handled in time, Nintendo have been working towards that for a while now, so that's a non-factor too. Once that happens, and they fully adopt an iOS/Android-like environment (as they will, Iwata has stated so literally) there's no reason they wouldn't keep  their (old) games available for basically eternity. Your orinal discs are more likely to have become scratched and/or lost by 2034, so yeah.

I find it sad that even the first xbox had more memory than wii u ....

Moderated,

-Mr Khan