Not that I like this feat, but I think you could amend it to avoid that design flaw:
The feat allows a character at any point during a full attack action to sacrifice all remaining iterative attacks to ready a single attack. Her readied attack uses the attack bonus that her next iterative attack would normally use.
Thus, a fighter with this feat and a BAB of +17/+12/+7/+2 could decide to attack once (at +17) and ready an attack (at +12); or she could attack twice (at +17/+12) and ready an attack (at +7); or she could attack three times (at +17/+12/+7) and ready an attack (at +2). If she wants her readied attack to be at a higher attack bonus, she'll have to give up all remaining iterative attacks.
Daniel