I'm afraid that's not possible yet. Maybe in a future OS release. This is a legacy of the Blackberry mail handling architecture from the days of no html/text only email. And because internal storage is limited and critical for proper operation of the BB. Older models never supported memory cards so RIM made you choose what attachments you wanted to save. The extra step is there to preserve as much free internal memory as possible. Kind of like with cars requiring you to put your foot on the brake pedal before it will start. Safety first!