Personally, for me, the reason I haven't made the jump to an NFA item such as a SBR or a suppressor is simply a result of unfamiliarity with the process. I've never jumped through the legal hoops to buy an NFA item. From my perspective the process looks rather daunting.
It's actually very simple, especially if you use a Revocable Living Trust as the registration entity- fill out the forms, cut the check, mail it in. The daunting part is waiting for your form to go pending (about 3 weeks from check cashing) and waiting to recieve your approved form back (4 to 34 days after approval- usually 4 to 14). Calling NFA Branch only makes the process that much more daughnting.
The first time is worst. Jump in the deepend and the cold water is nothing.
Drop the paperwork and I'd be more than happy to pay a $200 tax (which, without the paperwork, might actually generate legitimate revenue for the Treasury Department) for a well made suppressor, or a SBR or SBS.
The forms themselves are very easy to fill out. Filling out a 1040EZ is way more difficult. They are necesary in that they serve as proof of tax payment.