[Kylotan]

This is just plain wrong. Typical text is stored in 8 bits, allowing 256 characters of which we rarely use more than 60, half of which we only use once or twice per sentence, and the rest of which are used with very predictable frequencies. That is very amenable to compression. On top of this, most of it is predictable and repetitive. It turns out that the average English letter can be stored in about 2 bits on average, so that's about 75% compression rate already. Just because certain naive graphics and sound formats happen to compress better, doesn't make 75% bad, or anywhere near the worst. 75% compares favourably to mp3 compression rates, yet is lossless as well.

Since 4 Dimensions advertises itself as having at least 60,000 rooms, and 20MB is the compressed size, then I'd assume they're using about 1-1.5K of data per room, which is quite high for a Diku-derivative. Perhaps their builders put more effort than usual into each room/object/mobile; even more reason to back it up frequently.

I wouldn't. But it's obviously important to Molly, and presumably to their players. Who are you to mock this choice, really?

The players care. If they didn't, they wouldn't play. And one of the things they care about specifically in such games is the persistence of their character.