It’s not designed for pro SNO, that’s true. We always ask to use what is already online, so costs already paid.
Held amount is negligible long run as correctly mentioned by @andrew2.hart, but you of course right too, if you start with a new hardware and make it online only for Storj - it likely will not worth it, because it will generate costs at start instead of revenue. It may generate profit after a long run though, but it’s highly depends on your costs (not an advise), see Cost of running nodes?
The second thought - pro (expensive) hardware is not required, storagenode can be run even on the router: Running node on OpenWRT router?, using a pro hardware will not give any preferences in Storj network.
So, at the moment using non professional storage is a benefit. It can be so even for professional hardware, if it’s used not only for Storj, and you offer a not used space to the network. In this case, all costs have already been paid and all income is net profit, this will be a discount to your bills.