I can sort of see why they have done this given that the Nautilus 2 can be a pain to fill. When I first got mine I used to fund liquid all over the inside of the sheath bit. There were also plenty of people who had issues with the coil and all coming out when increasing the outer bit.
However as posted above, a better solution would be just make the glass tube and protective bit one solid component and have a normal top fill lid.
New 0.4 coil could be interesting - granted I have minimal experience compared to most here but I have always quite liked their 0.7 coils.
Wonder what a better alternative tank to this one would be?