You do if you want to continue doing what I do (Graphic Design).
Many of our customers (including the Citys of Glendale and Peoria, Arizona) send ads and legal documents in .docx format. The City of Glendale's weekly cable guide comes in .xlsx format. Word 2000 and Excel 2000 on a PC will not open .docx or .xlsx. I cannot open late version .ai files with Illustrator 6. How do I open a late version ID file with Adobe Pagemaker 7? Acrobat 5 for camera ready PDFs with no Quite a Box of Tricks and PitStop Pro? Photoshop 6 Educational for modern PSDs? That's just the stuff coming in.
Going out? The printer want's PDF/X-4:2008 That's NOT even in cards for Pagemaker 7. Sure I can export a postscript file or a series of EPS files. But Acrobat Distiller 5 does NOT have the option to create that PDF format. We're screwed unless we update (which I have forced over time to what we have now).
Sure, you're right if your own isolated process is all you have to meet or what you do matters only to you. But sooner or later outside forces will force change on you and my industry does not exist in a vacuum. There's one print customer we have who is about to experience this as there will no longer be anyone available to shoot his pasteups to negative, burn plate and then mount the plates on a press. All the printers in metro Phoenix want PDFs. So, his choice is to buy a computer and the software to produce his paper electronically or fold.
NOTE. I am NOT arguing against PowerPC. For my own personal purposes I prefer it and I have more than one PowerPC Mac in my home. But web browsing, light word processing and email, occasional design work is fine as it's not what I depend on for my income. But at work, it doesn't and hasn't since 2006 cut it anymore. I don't particularly like the newer Intel Macs too much, but I do need them to keep up so that I can do my job.
Adding onto another field where powerpc is useless is gaming and video editing,
no game being made this year runs on powerpc period.
video rendering is very very slow even on powermac g5 quads. They all have a total of 10Ghz and can't be overclocked. my current workstation is more than 3 seconds faster per operation and is not even at its max clock.
now supporters would argue that 3 seconds is not a big deal, 3 seconds per second of 1080p footage rendered means that if you are rendering an hour of 1080p a g5 would Finnish half an hour behind my pc.
they are just not useful in the pro market either