Because Apple is the only serious example we can refer to as of now: Apple pushes something fairly new, technologically year after year; nonetheless, that didn't cause them to drop support of older products, as you stated yourself: not only do you still use your 3GS, but Apple actually still keeps on making and selling new ones.
*LTD* 's point was that the industry needs more companies like Apple that have a true commitment to delivering value to their customers, instead of ushering mediocrity into the market, for the sake of getting more Ad-views (Google) or selling more licenses (Microsoft).
The last decade has shown clearly that it's Apple's model that moves things forward, technologically, because the vertical integration forces the company into accountability for the entire user experience. There's a lot of new technology invented or discovered out there, all the time... but the tricky part is to translate it into something useful and usable for the market, and it's the part where the industry as a whole tends to suck big time.
The user-experience centric model is the only one that will make things advance, and it's meant to deliver consumers' satisfaction, not 'raping' like you suggested.
