The arrogance of trying to design for long term storage management
Many systems seem to be not really designed for a long term storage management environment. Instead they seem to opt for a kind of planned obsolescence approach where they assume that you will buy them, run them more or less into the ground without really changing or upgrading anything, and then replace them wholesale in a big, painful, user-visible bang.
From the perspective of a long term storage management environment this is a crazy thing to do; with no growth and thus no future, these systems are basically closed boxes. If you outgrow them, you're in trouble.
But from another perspective, the long term storage view is itself crazy: when you adopt it, you are betting that you can pick out what will be a good environment in five years or more, one that it will still make sense to expand and add on to. Given the rate of change in computing, this is a pretty breathtaking bet, one that has historically gone wrong more often than it has gone right.
In a way, the 'run it into the ground' approach is much more humble. It doesn't try to do anything more than pick what's the best for right now, and just assumes that in a few years from now the tradeoffs will be so different that there's no use trying to predict the winners in advance.
(If you need expansion in a year, or in two, you just buy whatever is the best at that point and hook it into your environment. In the mean time you aren't paying extra for bets that probably won't actually be right.)