I think that some of the people commenting here and complaining about how slow 5400 rpm drives are aren't aware as to what 5400 rpm actually means. It is not the sole measure of a hard drive's speed and being 5400 rpm does *not* mean it's super slow. It is purely a measure of the *rotational* speed of the platters in the drive. While it is true that a 7200 rpm drive *with all other specs identical to a 5400 rpm drive* would be able to read data faster, there are multiple other factors. A drive also reads data faster if it is higher capacity per platter (the data is closer together and per revolution, more can be read), if it has more platters (multiple platters can be read at the same time) and if it is bigger (a desktop hard drive will be faster than an otherwise similarly specced laptop hard drive as there is more data being read per revolution further out).
There are genuine reasons for wanting to go with a 5400 rpm drive instead of a 7200 rpm drive - mainly that they are significantly less likely to fail and within the 3 years of AppleCare most people get, the hard drives are by far the most likely parts to fail as they are the mechanical parts that see the most use (optical drives similarly have a high failure rate which might be part of the reason why they're not included on Macs anymore).
If I were to complain about the standard hard drives in these models, I wouldn't be complaining that it's a slow 5400 rpm drive, I'd be complaining that it's not a *higher capacity* 5400 rpm drive. Chances are, a 2TB 5400 rpm drive would actually be faster than a 1TB 7200 rpm drive anyway. Although, I'm guessing that Apple is keeping the mechanical drive capacity option low so that the SSD options look more tempting.