Wrong many people buying this machine do need a 128 card to justify it, soon Games will need that, Apple themselves brag on it being a game machine, I guess you disagree with them, I doubt those are the only thing people will do with this machines 1.6-1.8 G5 processors, thats a put down,on Apple BIGTIME!!.
THe Problem is the G5 is being crippled by a crappie graphics card. with that bus and memory and power. why bottleneck it with a crappy card. people are not asking for the ATI x series or even 9800 or Nvidia's 68000. they are asking for a chip better than the Imac G4 chip, progress you know, and with 128MB memory, and they will pay BTO to have it.
A good incentive is BTO and the $$$$ it makes with Apple being the only provider of the cards. This may happen. some people dont want or need the hhuge dual powermacs and the fastest video cards, they need the Imac G%with a simple recent fast card with 128MB.
Get over it yourself, take a poll of Macrumors, and you would see that many would like that paid option. but you are correct many dont, along with schools, businesses, light computer users. but for them there is the Emac, and old left over Imac G4's, shouldnt the Imac G5 have a better card than the outcoming Imac G4, at least as an BTO option.
I think that is a fair question, and Apple may have one planned for later, in fact I am almost sure they do.