I would balk at taking a 1 in an Attribute, both for mechanical reasons (you can't default unless you have positive modifiers) and for metagaming ones (it is one of those things that can really push the buttons of some GMs). But someone with a Strength of 1 can carry 10 kg (about 22 pounds) without being encumbered, and can do normal physical tasks that would not normally require a roll to accomplish. So someone with a Strength of 1 is a couch potato - not an invalid. Likewise, someone with a Logic of 1 could be a lazy thinker who gets most of his opinions from the trid, and hasn't learned how to use half of the standard features of his stock commlink - not someone who needs to use his fingers when counting.
An Attribute of 1 is low enough that it can be described pejoratively - weak, dumb, etc. But I balk at the more extreme characterizations of low stats - because they can be improved so quickly and easily later on. 10 karma, and you have an Attribute of 2. 15 more karma, and now it is a 3, indistinguishable from the masses. It makes sense for the dumb troll ex-bouncer who has to use his brain, to step outside of his normal role and try to make it as a freelancer. Or for a basement-dwelling hacker who has to run for his life, huff and puff his way over a chainlink fence, and wheeze as he drags a wounded dwarf teammate to cover. It doesn't make as much sense for the more extreme characterizations of an Attribute of 1.
An Attribute of 1 is, in and of itself, not an indication of poor roleplaying. I would at least check the character sheet, to see how the character's stats are reflected in the background. Personally, I think an Attribute of 1, just like an Attribute of 5 or 6, is something that stands out from the norm, and should be explained. That goes double for lopsided builds (things like Body of 5 and Strength of 1).
One way to address min-maxing is to give players more points. If people are taking dump stats and bare bones skill allocations, then maybe it is because they feel that their resources in character creation are too limited. It may seem a bit counter-intuitive, but sometimes, if players don't have to scrimp and squeeze as much to get a character they are satisfied with, and can get what they want and afford some nonessential things, they will min-max less.