Can you cite any sources? I've been going through some other airline liveries and most of the large airlines make their logo as big as they can on the tail (like Emirates, Air France, BA, Qantas, Malaysia, Singapore, etc. - I was going through the A380 liveries and the only one I saw with a smaller logo on the tail is Lufthansa). I'm also pretty sure all major airlines in the US have larger logos too. I personally think it looks a lot nicer that way too. Also, Just another personal opinion - I prefer the old logo to the new one. I agree the new one is a little cleaner (fewer lines), but the old one has this majestic and powerful character to it the new one doesn't (think it's the lion's mane).
Maybe try the old tail logo with some of the newer designs?
Cheers
EDIT: Here's a screenshot of the "Dolphin livery" (I see it has quite a few votes) with the larger logo on the tail. Consider just the tail - I didn't spend much time on the curves aren't correct as compared to the list of liveries posted earlier.