(Inspired by 5ives)
- The fact that I can't snap a perfectly harmless picture without the phone emitting a loud, silly noise (and not necessarily a "camera click" - some phones chime) to let everyone inside a 20-meter radius know I have an expensive (and muggable) phone. It's stupid, does not solve the basic problem of preventing camera phone misuse (no matter how many privacy issues are at stake), and it actually makes me take less pictures. As Schneier would put it, this is "security theatre" and actually detracts from usage.
- The built-in browsers still suck. No matter how much XHTML support handset manufacturers say they have, the content support, the rendering, the UI and interaction model are all pretty much useless. Opera fixes most of this, but it only runs on a very small percentage of phones (no matter what Symbian addicts say) and is therefore largely irrelevant. It's not just about software - the most obvious ergonomical improvement (a side scroll wheel) seems to be a niche feature.
- The fact that I can't simply select a picture and e-mail it instead of jumping through a series of hoops (you wouldn't believe how deep the "attach file" option is buried on new phones). MMS is unusable - over-complex MMS editors on phones and the new trend of wrapping MMS-to-e-mail messages in HTML make the whole experience confusing and frustrating for novice and non-tech users, who don't really understand the difference between MMS and e-mail anyway.
- Crippled Bluetooth. I guess it never crossed anyone's mind that Bluetooth security problems can be fixed by, er, actually fixing them (and maybe removing some troublesome AT commands that provide phonebook access) instead of removing the whole OBEX stack. Not being able to easily swap phone numbers, beam my contacts to another phone or upload photos to my Mac just because some kid figured out how to send AT+CPBR to a Bluetooth serial port (which, incidentally, is not the same as the OBEX service) is ridiculous.
- Proprietary data cables. I can't think of a single serious reason for not having a perfectly ordinary, standard mini-USB socket on a phone for modem access, syncing, etc. (and trickle charge through it). It would save untold hours of frustration for users, and it can't be about forcing them to purchase an extra cable - most phones now come with data cables in the box.