Obviously I'm a little biased, and I am not at all trying to say that Maemo Mapper is better than Google Maps, but for the record, Maemo Mapper can do all of those things that you mentioned:
So does Maemo Mapper.

Maemo Mapper's zoom is hardware-controlled, which in my opinion is nice.

Maemo Mapper can operate without a backing map database (i.e. zero disk usage). It still caches maps in-memory, though, for quick access.

Maemo Mapper has a "double pixel" mode which basically shows half the resolution (and thus uses a quarter of the bandwidth), which I think maps exactly to the Palm emulator's resolution.

(Maemo Mapper still uses as much screen as it's given, though, unlike the Palm emulator, so if you're so inclined, you can consider that a negative since that technically requires more bits.)

In addition, Maemo Mapper gives you more control over which zoom levels you want to view and download, so technically you can go beyond the "double pixel" option to quadruple or 8x viewing for even more bit-efficient usage.

This is (of course) subjective, but I think Maemo Mapper is pretty easy to use, even if it's not to the level of Google's standards.

Maemo Mapper uses OpenStreetMap.org maps by default, which is perfectly legal and not even against their policy. In fact--kudos to them--they actually went out of their way to provide a Maemo-Mapper-compatible web interface.

It is true that Maemo Mapper can be configured to access maps in a way that may violate some services' terms of use, but just because it can doesn't mean that it must.

Honestly, so would I, as long as it didn't require a constant internet connection. I wrote Maemo Mapper some two-and-a-half years ago because there was a clear gap in the market. There are a couple of new players in the game nowadays, but unfortunately none of them is Google.