True, package executables are kept on disk by apt, however they are really small. Kernels don't take up much space either. A linux / partition with lets say 25 GB of space allotted will, even with a bunch of packages installed to it still only use about 60% of that available 25 GB at max.
In my opinion people carry that old mentality of the days of 10 GB disks and windows to linux. They remain paranoid about space. On Linux there really isn't too much of a need to be concerned unless you didn't allot the proper size to your / partition when you made the installation. Even if that is the case in most cases you can simply expand your linux / partition. At this point I must note that I have separate NTFS disks/partitions for my files. I do not save them to linux /, more specifically /home. This has benefits. I can clean install or restore an image if necessary without having to move files from linux so they are not overwritten. I can then access them from any OS. I currently have Arch, Ubuntu Windows 7 & 8 on my machine.
In my /var/apt/cache/archives directory I have 412 items which only total 702 MB. Really? Are they consuming that much space? If one wants to remove these stored downloaded packages that is OK. But they should not be consuming too much space to get someone worried in the first place.
I am by no means an expert. I have been using linux for almost 8 years. I have used ubuntu, mint, crunchbang, fedora, sabayon and arch. I have never had a problem with space on /. Probably because I allocate 25-35 GB for the / partition. Given the size of most users hard disks this is a concern of days gone by.
Output of df -h terminal command from ubuntu (sda3), sdb 1 is my storage, sdc1 is my internal backup: