Slow adoption of legitimate torrents

It's kinda cool that this is the first job I've had where I'm expressly allowed by IT to run a BitTorrent client on the company network, for use in pulling-down large ISO's (primarily Linux distributions for testing under virtualization). Actually being able to leave Transmission running on my Mac Dock is pretty neat, and I'm impressed that my employer's IT staff came to the rational conclusion that a bit of upstream traffic was a reasonable exchange for the massive improvement in downstream retrieval.

However, that adds to my frustration when stuck trying to download large DVD-sized (4GB+) ISOs from the likes of Microsoft and National Instruments (LabVIEW) who have not come to the same conclusion, and still expect you to pull down such huge files via point-to-point mechanisms. Anyone who's used browser-based downloads on such a scale knows too-well the pain of a broken connection 3.9GB into a download, many of which "cannot be resumed" and leave you with a useless .part file.

Of course, some vendors are happy to fill that gap with proprietary executable "download managers" which claim support for resuming broken connections. However, such managers are almost always provided as Windows-only executables and have several problems:

• All my machines are laptops, e.g. designed to be closed, moved around, shifted between IP networks, and periodically go to sleep (none are high-uptime server-class desktops).
• My "best" machine for downloading large files is a Mac, making .exe download managers futile. While I can run Windows in a VM, I'm bouncing between different Windows VMs and snapshots all day, and being stuck running a single one just to maintain a download obstructs my flow.
• Many download managers (and many websites) decide to be "clever" and automatically detect what operating system your browser is based on, and therefore auto-select what version of their software you must wish to download, and then refuse to allow you to alter their selection. I've actually encountered several products which refused to allow me to download a Windows version from a Mac browser, or vice-versa.
• Yes I know about "wget -c" and so forth, but not all download sites expose a canonical, persistent URL (too many are based on session cookies and dynamically generate redirection URLs from .asp logic and whatnot).
• Torrents aren't just more robust, they're demonstrably faster. I'd far rather pull the contents from a few local seeds on adjacent networks than rely on a single pipeline from the primary vendor.
  

All in all, it would be so much simpler if legitimate software vendors would make increased use of powerful, reliable, standards-based tools like BitTorrent to distribute their larger (>1GB) offerings. With easy SHA1 and MD5 checksums, there's no real risk of malfeasance, so...what's the obstacle?