personaly i think sideways mounted harddrives don't get cooled correctly ,
i know this as a fact as i've had 2 cases and the one i have now with a side mounted fan just doesn't cut it even after drilling big holes
pictured here
http://img.techpowerup.org/091013/more holes cut and cleaned.jpg
there is no way they can unless you have mountings with huge holes,
and well they just don't exist, so this Azza case has the benefit of keeping the drives alot cooler,
yes sideways mounting harddrives are a alot easier to put in/take out, but what use is that if they overheat and make more noise?
+1 for being technically spot on.
For the most part, technology has advanced enough to where 3.5" Sata is the standard nowadays where not long ago it was 3.5" IDE and I can even remember 5.25".
Cases were/are designed to accommodate a multitude of system configurationss some of which may possibly include IDE drives still to this day even believe it or not. Hell, I still have 2 IDE HDD's myself in my main rig.
Average Hard Drives are small enough and the mechanisms within are sturdy enough that mounting HDD's in any position and at any angle is not so big a deal as it used to be. But they still need to be accounted for in high performance systems where massive amounts of heat is generated and most case intakes are designed to be in the front lower area, usually where air is coolest and it just so happens to be where hard drives are mounted. Hard drives are mounted with the mounting holes on the sides and if you build a mounting mechanism to accommodate all 6 screw holes of 4-5 hard drives, then well, you will end up with a wall of metal blocking your main insource of cool air.
There are always around it, but by design it is just more efficient to ensure that hard drives are mounted in a way that cool air is pushed/pulled/forced in some way from front to back with no more resistance than is necessary.
I have 7 different computer cases right now, each with 2 Hard disks mounted in them and each with an intake fan, although varying sizes, that pretty much blows directly onto the hard drives from the intake, thus cooling them, as well as offering cool air to everything else, with the exception of my Dell XPS 410, which has the side to side cages on the very bottom floor of the case, and there are only 2 of them total with no room for expansion because they are side to side. All the rest are front to back.
The Dell XPS' ambient temperature hovers around 45 degrees celsius average and the hard drives run at a minimum of 6 degrees celsius HOTTER at idle than the hottest OPERATING Velociraptor in the crappiest case I have, which is pretty crappy (It's small, cramped, and very crappily built and designed; but I use it solely for testing anyway, so who cares.)
In addition, this extra heat transfers to everything else and does not help cool anything. I even had to cut a hole in the side for extra intake as well as buy 2 fans for the rear since it didn't come with them. Dell is stupid like that, but the case is pretty.
So while I am sure it's just really a cost/efficiency factor rather than cost/convenience factor in budget cases, it is likely the more expensive the case the better your chances of seeing multiple mount possibilities in HDD cages.
