I'm amazed by what you get on the base Sport. Granted I haven't been in the car market in 9 years - but I do go to the NY Auto Show every year - and I'm surprised at how relatively little distinction there is in the Mazda5 model line. I would have thought that you'd have a lower base model and a higher top of the line. (And I'm assuming that most base cars today would come with floor mats, full carpeting, 6 speaker stereo w/CD, automatic transmission with manual shift ability and a tire pressure monitor - which is now required by federal law. These are all things that 10 years ago you paid extra for - but let's just keep them out of the picture. Where I am surprised, even by modern standards is the base Sport having 17" alloy wheels, body colored mirrors, automatic climate control, drivers seat w/height and lumbar adjustment, tilt/telescoping wheel, audio controls on the wheel, 2nd row seat storage & mini-table etc. These are all things that I would expect to be "withheld" on a base model - but they're not.
IMHO, Mazda really relies on the moonroof to carry you to the middle of the line (and I do know people who feel it's a must have) and the leather and Bluetooth, heated seats, fancy rear view mirror etc to pull you to the top of the line. Although those things are great - on my budget, I was absolutely thrilled to get all of what I think of as middle and upper line features on the base model.
I guess the most direct competitor in my mind - the Kia Rondo comes similarly equipped - if not slightly more so. (And there are plenty of less direct competitors in my mind - I know I was also considering a RAV 4 - but it was considerably more, as you had to buy upwards [requires 4x4 model vs cheaper 4x2] to get the third row seat option – which was a make or break feature for me.)