I fully agree with you. I have a 64 Gb 3G iPad 2 (the best one, at least in Italy) and I am frustrated as well by all the issues that you pointed out. In addition to that, I was stunned by the fact that, apart from the screen size, I can actually do more things with my Galaxy 2 (Android) than with an 800 € (!!!!!!) larger device.
Another frustrating issue is the lack of a real usb/wireless file transfer: I either need iTunes (but I'm running my PCs on Linux) or a network, and in any case it's awkward. Any other device in the world can be plugged in as a USB drive, but not the iPad. Lack of flash support is frustrating as well, since many videos are not yet HTML5 compatible, and the other browsers are either buggy or not smooth (2 frames/sec)
Not to mention the fact that the iOS version of many applications (e.g. Outliner or remote controls), if at all available, lack in functionality when compared to their Android counterparts.
Finally, the apps in the appstore are on average twice as expensive as the ones in the android marked.
I have already decided to sell the beast in favour of an eee transformer: it will be less stylish, but when used on the field for real problems will top the bill.
Concerning the subject of the post, I have often the need to send, in one email, different files, for example a spreadsheet and and a word doc, or a photo and an office doc... It should be done from within the email app, because otherwise I am forced to send separate emails, one per each attachment, which is cumbersome and prone to errors (one email can make it thru and another be put into the spam folder and not be noticed by the recipients).
That's why I landed here in the first place: I thought I missed some shortcut, but to my disbelief looks like it's actually not possible select attachements from within the email app.
I'll update to iOS 5 as soon as it's available, but from what I've read so far about it, things are not going to change a lot. What a pity.