Fundamentally it comes down to you having to pick the battery you want to use and the leds you want to use.
By choosing blue leds you set a lower voltage limit for the battery voltage you can use. If you instead choose red leds, with their 1.5Vf ratings, then you increase your battery choices.
It's like that old adage, lower cost, quicker schedule, better quality, you are only allowed to choose any two. 
Lefty