As far as RAM is concerned, the screenshot seems to be from a beta firmware. There's over 300 MB in the final version, you can look up newer screenshots if it matters much for you. This is a lot of available RAM if you ask me.
As regards the flash memory, the ROM image is over 300 MB, which leaves around 200 MB available. There's a lot of stuff there including navigation software, and the new Manila aka HTC Sense is huge. Custom ROMs may free around 30 megs or more by throwing away stuff like CoPilot (which belongs on the storage card, IMO), and if you don't like Manila you can probably save another 50 megs or more.
I'm not sure this will help you feel less "disgusted" though, but hopefully should count as an explanation.