I have to admit, I'm a little lost/confused about the need for a massive boot with kids. I appreciate that things have gotten bigger with safety, but when I was a kid I remember families coping with original minis and kids - hell, my dad had a 2 seater X1/9 when I was a baby and he only got a 5 door when my brother was born.
Surely a pram will fit into any hatchback??? I moved from a MX5 to a 1 series in the fear that the gf was talking about kids - and now we're expecting one, I'm a little confused why the mention of kids suddenly moves towards estates and SUVs... yes, I fully expect to be eating these words when I'm wrestling with multiple bags and just wanting to chuck items into a space, instead of pack semi-methodically.
back to 1 series boot-space - tbh, I find it massive (but, then, I could pack a weeks shopping into a MX5 boot) and arguably more usable space than the gf's Countryman, with the 1 series lacking the height axis.