Atomized B44 with a 2+2+2 layout is a challenge, yes!
I've got it myself and went for a LiPo special version which takes 3200 TrakPower saddles.
Anyway, those who want can still run NiMH - and will.
As to keeping a set of size restrictions for OR the only thing that can be gained from that is a 100% direct fit in most mainstream chassises.
But if someone want to carry excess amps - why stop them doing that? I love my Dremel and find mods a big part of the fun...
How about simply splitting the list in half? One part with approved cells that are within the size limits. And one half with bigger ones that still are tested as to crash, shorting and overcharging. Then it will be crystal clear as to whether a pack fit your car or not...