G4 = Athlon
You're right that on the whole, what one might call 'normal' users of Macs don't need any extra speed - for their applications. I will agree with you that many apps run fine on a G4/400 (mine is as well).
However, with Mac OS X, expect to lose at least 30 per cent of your productivity. It's a really nice OS, it's just so g o d d a m n sssssllllooowwww. In fact it is slow about everything except network handling. But anything that requires the Aqua interface to spring to life, is way way slower than the same task performed in OS 9. In spite of the seemingly smooth and simple interface, everything in OS X requires more clicking and dragging, and waiting - and waiting. Sure, the wait duration is reduced when one uses a faster processor (and I'm sure the guy with a DP800 doesn't feel my pain), but it's still there. OS X waits for everything: click a folder, oops gotta search the file system for the contents, scratch scratch on the hard disk, then 5 seconds later it lets you have that file list. Oh! But woe betide you if you dare to scroll that file list, scratch scratch now where did I put that file list, oh, there, no, wait, crrrr.. crrrrrrr... it's just no use to anyone.
In OS 9: boom! It's nearly instantaneous. People tend to forget that when they wax about OS X. Yes, it's great that we finally have a pre-emptively multitasking operating system. It's great for *some* things. But by and large, the good old collaborative multitasking in OS 9 does everything *better* and *faster*. Sure, it's not secure (but then who needs server-level security on their home computer? Why do you have to login as root to save your window views?!!? Why DO you even have to login to your own personal computer?). Sure, it's doesn't do X things at the same time. It crashes. Sometimes. But then you do know that so do OS X apps, don't you?
In OS X, not even Word 10 is there for you, responsive. Try to measure the time it takes for Word 10 to catch up with your typing! I know that no programmer could stand that from their dev environment! What the hell is it doing? All it's supposed to be doing is waiting for you to press that next key. That's all! But even that, it can't do properly.
So what's wrong then? I lay the blame on Aqua. And maybe even more so, I lay the blame on Carbon. I wonder if any of us have ever even experienced true Cocoa code run. Everything (that matters) is being carbonized, because no-one, simply no-one, can afford to start their app development over from scratch, teaching their coders a new OS, a new dev environment, AND a new programming language to boot! No wonder Adobe, Macromedia and the rest are simply carbonizing their stuff. No wonder it is slow as well. Nothing is being optimized. Nothing!
However, Apple's true customers, the Wintel-to-iMac crowd, will never feel any of this pain. They will get the great white hope (the new iMac) and go right ahead and use the i-apps, which are the only apps out there coded from the ground up in Cocoa. Even Word and Entourage (shudder) will feel responsive to them. Because they'll have a 700 Mhz G4 and a lo-res desktop, it'll run just fine in OS X. They'll be playing Harry Potter and Otto Matic, it'll run fine. But what about the kid who gets a new iMac because he thinks it's sexy and he wants to play Return to Castle Wolfenstein on it? Have you tried the beta under OS X recently? You're lucky if you can get 15 fps.
Alas, I come across as a Mac basher. But I love Apple! I love the Mac!
All I want is:
a) proper G4 processor speeds (1.4+ Mhz) which will make me feel good about my Mac again (and maybe even OS X)
or -
b) an even better processor (the G5?) which, at the sorry speeds that Motorola can churn out, actually beats an Athlon in a real-world test (and no Phil Schiller hand-picked-the-only-3-Photoshop-filters-that-can, thank you)
c) DDR RAM and a 266MHz bus
d) a BTO GeForce3 Ti-card at REAL competitive prices, not 2x the street
e) BTO RAM at REAL competitive prices, not 5x the street
f) and, you know, while we're at it, I wouldn't mind a double button mouse
Is it really all that much to ask?