Apple does not reply to questions in these forums. We're all just fellow users here.
As to why the iPhone 3G does not support all the newer features, that's been discussed in these forums at length, and it mostly boils down to the hardware not being able to support those new features, either at all or at an acceptable level of performance. If you wish to comment to Apple on the issue, though, you can use their feedback page:
Ya but there not new features... I'm not talking about the ones compatable with IPhone 4 I'm talking about the old ones that were on the phone before like backgroud wallpapers multitasking ect. You do realise that people are jailbraking the phones to get them... If i were you I'd rather make an update so the users could use all the features that we paid for. It's not right on our side...
There are no features that were previously available in the iPhone 3G that are no longer available. Ther are features in iOS 4, such as wallpapers and multitasking, that the iPhone 3G will not support, not to a level that Apple considers acceptable. Yes, some features can be had by jailbreaking, but they do not work well; people just live with the problems.
If you were me, you couldn't make an update, by the way, since you would not work for Apple (no one who responds here does, as I said) and could not do anything of that sort.
Anyway, you've been given the way to comment to Apple. There's nothing more anyone here can say.