Maybe you're just doing it wrong.

1. Attaching photos to email: Ok, honestly I don't try that too often; I don't use my iPhone or my iPad as my primary email device unless I'm away from my desktop (I spend a minimum of 12 hours per day at my desk.) However, if you know you're going to attach a specific photo to an email, then why not just click the photo, select 'email photo', address it and write your email text from there? It even gives you a choice of what size to make the image when you send it. Couldn't be simpler. Of course, if you're wanting to send several images at the same time, I might agree with you but I just experimented and found I could send any number of images from my iPhone just touching and holding the first image to bring up the 'Copy' button and selecting a number of images, then touching "Share" to email it. Hardly any more difficult.
B. I might agree, but honestly I've never had the need or the reason to even try. If sharing photos is so easy, I doubt sharing PDFs is any more difficult, though you might need to manually enter the recipient's address rather than just touching 'Reply'.
C. I'm not sure I understand this excuse. What do you mean by "collapsing folders"? Getting to a folder view is quite easy (just touch the 'Mailboxes' button) and you can open any of the other available mailboxes individually. Certainly not difficult.

2(a, b, and C). Restrictive nature of using iDevice as storage: Umm... It's not intended to be a "storage device"? It's a fully-functioning nano-computer--capable of processing data on its own. You want a separate storage device? There are tons of far-less-expensive portable drives and Flash drives that serve that purpose more readily. Even so, there is software readily available to let you do that on the iPhone if you want. I really don't understand the desire.

3(a and b). Now I know you don't know what you're talking about. I share screens and videos (including Keynote/PowerPoint presentations) using my iPhone or a first-gen iPad through an sVGA projector on a regular basis. Admittedly, if the new iPhone does drop the sVGA contacts from the new connector you'll probably have to use a wireless receiver on your projector. A simple $20 cable is readily available and the AppleTV makes a good wireless set-top box if you just have to go wireless. Either way is still cheaper than most alternates I'm aware of.

4. VPN -- Are you trying to VPN into the phone, or out? Certainly VPN is available in iOS and I do believe it works for the iPhone as well as the iPad; however, most people want to VPN out of the device to a desktop and that's certainly easy, though some network settings don't permit mobile VPN too readily.

5. By "Network Browsing" I must assume you mean 'finding other computers on the network." Honestly, that's not the purpose of a smartphone nor is it the purpose of a tablet--yet. Smartphones are PC supplemental devices, not yet full PC replacements--at least for the enterprise. Why do that when you can VPN back to a desktop that already has that access?

7. WiFi issues seem to be quite device independent; I read of even Samsung Galaxy III models having WiFi issues. From what I've been able to glean from research, more often the issue belongs to the network settings on the router rather than any phone-specific issues. This could be something as simple as placement of the antennae around the building, too.

8. Ok, up until recently PHONES were not intended to be playing STEREO music through Bluetooth headphones. This is especially hazardous when driving or walking as you simply won't hear even a train coming up on you to run you down. Really, you're promoting a very dangerous habit.

9. PDF reading compatibility. Hmmm... Let me try that right now. Hmmm... worked with absolutely no problem for me. I emailed a PDF to myself and opened it in my iPhone 4 and was able to read it, zoom in and out, turn, do almost anything with it I can any other type of image. I certainly didn't notice any data missing. Maybe you forgot to download the rest of the data?

10. Well, you're getting that wish--I think. Stylii you can buy anywhere, you're supposedly getting a "bigger screen" and as far as Bluetooth keyboards are concerned, I think they're unnecessary for a phone but the iPad is quite capable of using any Bluetooth keyboard on the market.

Overall, it seems that lack of effort on your part or simply lack of desire to try is all that's keeping you from making the iPhone a viable tool in your office. I'm using 2-year-old iDevices to do everything you say can't be done.