Probably uses less plastic, thus is cheaper to make. Any other benefits might be accidental! OTOH, the slope may be steeper, less need for dangerous, rain-repellant chemicals!
Not sure about those 'vents', however. While there's not much inside the area that would be harmed by water, it just looks like it could be more inviting for eight-legged, web-dispensing critters... On the third hand, it might make removing the whole thing a bit easier. The current slick-sided 'tub' can be difficult to get a grip on!
I've not found one of those oil filter, loop type 'grabbers' that is big enough! What size oil filters does a 74 use?