You've got a point - he does have a slightly long waist, which possibly makes these long straight lines look even better from his broad shoulders. I don't do sewing, but I do think it is called the 'drop'...
I found it interesting in the DVDs when Bruce mentioned how much he hated wearing the ties, as he wasn't a suit kinda guy, and we should look for when his tie changes length or angle throughout a scene!
I think Bruce has the right build and proportions to be able to wear pretty much anything and to look good in it. Even a babygro... :-)
"You can lead a horse to water, but that doesn't make it a duck"