Many, many companies do want this, yes. Back in 2005-2006, I worked at MP3tunes and among other things I helped design the storage system. After testing a bunch of storage solutions (many of them high-end systems), we ended up rolling our own using Linux + MogileFS. This was scaled up to a couple hundred terabytes before I left, and even higher afterwards. Sometimes the off-the-shelf solutions simply don't work, especially at scale.
Pretty much, the amount of times we've had issues with new storage vendor arrays from a 3 letter company that starts with an E, and ends with a C, is a bit too much to count.
Firmware bugs that affect anything on a fabric, that affect how it distributes its cache slot locks on writes, issues with the entire array acting funny, which are blamed on either the server hardware or os itself until proven to be an issue with the array (this is far too common to be honest, yay for "support" contracts), etc....
Yes you get "support", and I use the term lightly, with big vendors, but you also have to take a machete through their support organization to get to someone that can help you with a problem. At times rolling your own solution will end up being both cheaper and less problematic. The old adage of "Nobody ever got fired for choosing IBM" may soothe managers minds, but wait until you do end up buying those fancy pants high end arrays and find out how much snake oil turns out not to work on them.
