I downgraded to 3.1.3 its not too hard to do (cant give you links, apple consider downgrading jailbreaking they told me! but do an internet search for "iphone 3g downgrade 3.1.3" or remove iphone OS4...
dont worry it wont invalidate your 90 days warranty you get with your iphone 3G (im sure you bought it more than 90 days ago anyway)
basically all you need is the correct 3.1.3 firmware (might be in your recycle bin - iOS4 deletes your old one in the hope you dont find it - if not you can download it from a few places, make sure its the one for your model - iphone 3G)
hold left shift when clicking restore & it'll ask you which one you want to use (otherwise itll be the same 4.0.1 or whatever you used last, point it at the 3.1.3 one)
let it restore & you need recboot to finish it (& libUSB too especially if your using vista)
when I did it I lost everything so make sure you back up everything 1st.
but yeah, 3.1.3 works just like you remembered it & all the apps you updated to be 4.0 compatible still work with 3.1.3
&
http://www.apple.com/feedback/iphone.html - give them feeback - they wont reply, but if enough are logged maybe they will bother to do something....just dont hold your breath.