What makes them worth cardboard later IS that progress. Without progress my old Commodore PET or IBM PC or Apple ][ may still be worth thousands of dollars, but is that a good thing?
You say it's only to make them prettier, but if that makes them more immersive that may be part of it. If it allows you more realistic things like looking at enemies through the water while transitioning where they can fire at you and you can fire back without some artificially created barrier (water game plane / land game plane and never the twain shall meet) then that improvement is good for that style of gaming. Does it matter for Bejeweled, no, does it matter for a game like Bioshock, Oblivion, Crysis, etc to have realistic water effects, fog effects, and other 'prettier' effects, certainly it does, just like better shadows helped D3's doomed boring game be more worthy of the money spent on it.
Do I need a 2ghz Core2Duo to do my work? No, but if it saves me time or improves the experience then that is progress, and it's up to me whether it's worth it or not.
What you're complaining about is your perception of worth, not actual progress, nor even value, and the perception part is your problem. If you're happy with your 8088 rig but it needs replacing, let me know, cause I'd be more than willing to sell you one, and for you I'll be generous and know $100 off the original MSRP, and you can ignore all this fancy new 'progress' stuff.