I think the 32-gallon limit is because they're handled manually, so the workers have to lift them. They've gotten new automatic trucks for the recycling, and I'd guess they'd have to do the same for the garbage if they went to a bigger bin.

32 may be too small for you, but on a normal week I have only one or 2 grocery-store bags of trash which barely cover the bottom of my 30ish-gallon barrel. I do (to my surprise) regularly fill my recycling bin, so I don't regret its size, but I'd hate to have to have another bin of that size sitting empty in my yard for 4-5 days of every week, with one tiny bag in it for another couple days, and then two bags for one night. I hope if they go for big bins they're not a requirement.

I look around town and marvel at the amount of trash every other household seems to generate in a week!